Updated on 2024/06/22

写真a

 
OKAMOTO Yasuhiro
 
Organization
Faculty of Environmental, Life, Natural Science and Technology Associate Professor
Position
Associate Professor
External link

Degree

  • Doctor of Engineering ( Osaka University )

Research Interests

  • レーザ加工

  • Electrical Discharge Machiring

  • 放電加工

  • Laser Beam Machining

Research Areas

  • Manufacturing Technology (Mechanical Engineering, Electrical and Electronic Engineering, Chemical Engineering) / Manufacturing and production engineering

  • Nanotechnology/Materials / Material processing and microstructure control

Education

  • Okayama University   大学院工学研究科   機械工学専攻

    1996.4 - 1998.3

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    Country: Japan

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  • Okayama University   工学部   機械工学科

    1992.4 - 1996.3

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    Country: Japan

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Research History

  • Okayama University   Graduate School of Natural Science and Technology   Associate Professor

    2021.4

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    Country:Japan

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  • Okayama University   Graduate School of Natural Science and Technology   Associate Professor

    2013.4 - 2021.3

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    Country:Japan

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  • Okayama University   Graduate School of Natural Science and Technology   Associate Professor

    2007 - 2013

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    Country:Japan

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  • Okayama University   Graduate School of Natural Science and Technology   Research Associate

    2005.4 - 2007.3

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    Country:Japan

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  • Okayama University   Faculty of Engineering   Research Associate

    1998.4 - 2005.3

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    Country:Japan

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Professional Memberships

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Committee Memberships

  • レーザ加工学会   副会長・理事  

    2020.6   

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    Committee type:Academic society

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  • Laser Institute of America   Senior Editor, Journal of Laser Applications  

    2020.4   

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    Committee type:Academic society

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  • 精密工学会   中国四国支部 庶務幹事  

    2020.2   

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    Committee type:Academic society

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  • Japan Laser Processing Society   Editor, Journal of Laser Micro / Nanoengineering  

    2017.4   

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    Committee type:Academic society

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  • 溶接学会   マイクロ接合研究委員会 幹事  

    2016.6   

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    Committee type:Academic society

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  • 先進加工技術懇話会   幹事  

    2016.4   

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    Committee type:Other

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  • 光産業技術振興協会   多元技術融合光プロセス研究会 幹事  

    2011.8   

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    Committee type:Academic society

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  • 25th International Symposium on Laser Precision Microfabrication – LPM2024   Chair  

    2023.10 - 2024.6   

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    Committee type:Academic society

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  • 光産業技術振興協会   レーザー加工用光位相制御システムの市場開拓に関する戦略策定委員会委員  

    2023.4 - 2024.3   

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    Committee type:Academic society

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  • 24th International Symposium on Laser Precision Microfabrication – LPM2023   Co-chair  

    2022.10 - 2023.6   

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  • レーザ加工学会   第98回レーザ加工学会講演会副実行委員長  

    2022.10 - 2023.1   

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  • レーザ加工学会   第98回レーザ加工学会講演会 副実行委員長  

    2022.9 - 2023.1   

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  • Japan Laser Processing Society   Co-chair, 24th International Symposium on Laser Precision Microfabrication, LPM2022  

    2022.7 - 2023.6   

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    Committee type:Academic society

  • Japan Laser Processing Society   Co-chair, 23rd International Symposium on Laser Precision Microfabrication, LPM2022  

    2021.10 - 2022.6   

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  • (一財)光産業技術振興協会   光技術動向調査委員会 光加工・計測分科会主査  

    2021.4   

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  • Japan Laser Processing Society   Co-chair, 22nd International Symposium on Laser Precision Microfabrication, LPM2021  

    2020.7 - 2021.6   

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    Committee type:Academic society

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  • Japan Laser Processing Society   Co-chair, 21st International Symposium on Laser Precision Microfabrication, LPM2020  

    2019.10 - 2020.6   

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    Committee type:Academic society

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  • レーザ加工学会   第93回レーザ加工学会講演会 副実行委員長  

    2019.10 - 2020.5   

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  • 国立研究開発法人新エネルギー・産業技術総合開発機構   NEDO技術委員  

    2019.5 - 2021.3   

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    Committee type:Other

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  • レーザ加工学会   第91回レーザ加工学会講演会 副実行委員長  

    2019.1 - 2019.6   

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  • Japan Laser Processing Society   Chairperson of Treasurer, LAMP2019, The 8th International Congress on Laser Advanced Materials Processing  

    2017.12 - 2019.5   

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    Committee type:Academic society

    LAMP2019 - The 8th Congress on Laser Advanced Materials Proceesing;LPM2019 & HPL2019

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  • Japan Laser Processing Society   Program Chair, The 3rd Smart Laser Processing Conference  

    2017.9 - 2018.5   

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    Committee type:Academic society

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  • 精密工学会   校閲委員会委員  

    2017.4 - 2020.3   

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    Committee type:Academic society

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  • 国立研究開発法人新エネルギー・産業技術総合開発機構   NEDO技術委員  

    2017.4 - 2019.3   

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    Committee type:Other

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  • 型技術協会   型技術ワークショップ2017 幹事  

    2017.2 - 2017.11   

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    Committee type:Academic society

    型技術ワークショップ2017

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  • 岐阜県   岐阜県 研究課題外部評価員  

    2017.2 - 2017.3   

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    Committee type:Municipal

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  • レーザ加工学会   第86回レーザ加工学会講演会 副実行委員長,現地実行委員長  

    2016.5 - 2016.12   

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    Committee type:Academic society

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  • Japan Laser Processing Society   Chairperson of Treasurer, 18th International Symposium on Laser Precision Microfabrication, LPM2017  

    2016.1 - 2017.9   

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    Committee type:Academic society

    18th International Symposium on Laser Precision Microfabrication, LPM2017

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  • 溶接学会   中国支部幹事  

    2016   

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    Committee type:Academic society

    溶接学会

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  • Japan Laser Processing Society   General Chair, The Second Smart Laser Processing Conference  

    2015.12 - 2016.5   

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  • Japan Laser Processing Society   Chairperson of Treasurer, LAMP2013, The 7th International Congress on Laser Advanced Materials Processing  

    2014.2 - 2015.9   

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    Committee type:Academic society

    LAMP2013, The 7th International Congress on Laser Advanced Materials Processing

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  • レーザプラットフォーム協議会   理事  

    2014   

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    Committee type:Academic society

    レーザプラットフォーム協議会

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  • Japan Laser Processing Society   General Chair, The First Smart Laser Processing Conference  

    2013.12 - 2014.4   

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    Committee type:Academic society

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  • 岐阜県   岐阜県 研究課題外部評価員  

    2013.3   

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    Committee type:Municipal

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  • レーザ加工学会   第77回レーザ加工学会講演会 実行委員会副委員長  

    2011.11 - 2012.5   

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  • 精密工学会中国四国支部   幹事、商議員  

    2011 - 2020.1   

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    精密工学会中国四国支部

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  • スマートプロセス学会(高温学会)   評議員  

    2009 - 2011   

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    スマートプロセス学会(高温学会)

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  • 光産業技術振興協会   光技術動向調査委員会 光加工・計測分科会委員  

    2008.5 - 2021.3   

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  • レーザ加工学会   理事、評議員  

    2007 - 2020.5   

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    レーザ加工学会

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Papers

  • Effects of superposition of 532 nm and 1064 nm wavelengths in copper micro-welding by pulsed Nd:YAG laser Reviewed International coauthorship International journal

    Martin Ruthandi Maina, Yasuhiro Okamoto, Kazuki Hamada, Akira Okada, Shin-ichi Nakashiba, Norio Nishi

    Journal of Materials Processing Technology   299   117388 - 117388   2022.1

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    Authorship:Last author, Corresponding author   Language:English   Publishing type:Research paper (scientific journal)   Publisher:Elsevier BV  

    DOI: 10.1016/j.jmatprotec.2021.117388

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  • Effect of numerical aperture on molten area characteristics in micro-joining of glass by picosecond pulsed laser Invited Reviewed International journal

    Yasuhiro Okamoto, Zhiyong Ouyang, Takumi Fujiwara, Akira Okada

    Welding in the World   64 ( 6 )   937 - 947   2020.6

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    Authorship:Lead author, Corresponding author   Language:English   Publishing type:Research paper (scientific journal)   Publisher:Springer Science and Business Media LLC  

    DOI: 10.1007/s40194-020-00877-4

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    Other Link: http://link.springer.com/article/10.1007/s40194-020-00877-4/fulltext.html

  • High surface quality micro machining of monocrystalline diamond by picosecond pulsed laser Reviewed International journal

    Y. Okamoto, A. Okada, A. Kajitani, T. Shinonaga

    CIRP ANNALS-MANUFACTURING TECHNOLOGY   68 ( 1 )   197 - 200   2019.8

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    Authorship:Lead author   Language:English   Publishing type:Research paper (scientific journal)   Publisher:ELSEVIER SCIENCE BV  

    In micro machining of monocrystalline diamond by pulsed laser, unique processing characteristics appeared only under a few ten picosecond pulse duration and a certain overlap rate of laser shot. Cracks mostly propagate in parallel direction to top surface of workpiece, although the laser beam axis is perpendicular to the surface. This processed area can keep diamond structure, and its surface roughness is smaller than R-a = 0.2 mu M. New laser micro machining method to keep diamond structure and small surface roughness is proposed. This method can contribute to reduce the polishing process in micro machining of diamond. (C) 2019 Published by Elsevier Ltd on behalf of CIRP.

    DOI: 10.1016/j.cirp.2019.04.119

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  • Influence of Surface State in Micro-Welding of Copper by Nd:YAG Laser Reviewed International journal

    Maina Martin Ruthandi, Okamoto Yasuhiro, Inoue Reiki, Nakashiba Shin-ichi, Okada Akira, Sakagawa Tomokazu

    APPLIED SCIENCES-BASEL   8 ( 12 )   2018.12

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    Authorship:Last author, Corresponding author   Language:English   Publishing type:Research paper (scientific journal)  

    DOI: 10.3390/app8122364

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  • High surface quality welding of aluminum using adjustable ring-mode fiber laser Reviewed International coauthorship International journal

    Martin Ruthandi Maina, Yasuhiro Okamoto, Akira Okada, Matti Närhi, Jarno Kangastupa, Jorma Vihinen

    Journal of Materials Processing Technology   258 ( 8 )   180 - 188   2018.8

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    Authorship:Corresponding author   Language:English   Publishing type:Research paper (scientific journal)   Publisher:Elsevier Ltd  

    A method to improve penetration and stabilize the welding phenomenon at a high welding speed has been described through experimental and numerical investigations. Using a high power laser beam consisting of a center and a ring part, influences of shielding gas direction and flow rate, laser power density, and welding mode defined by variable intensity distribution have been clarified. The weld bead was evaluated in terms of width, height, shape and roughness. Dual-mode laser irradiation of center and ring power made it possible to stabilize the welding process. The center power helps to achieve sufficient deep penetration, while ring power ensures good temperature distribution. Good surface quality and deep penetration welding could be achieved with dual-mode welding, using low flow rate of shielding gas supplied from the backside direction.

    DOI: 10.1016/j.jmatprotec.2018.03.030

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  • Control of Kerf Width in Multi-wire EDM Slicing of Semiconductors with Circular Section Reviewed

    Yasuhiro Okamoto, Takayuki Ikeda, Haruya Kurihara, Akira Okada, Masataka Kido

    Procedia CIRP, Proceedings of 19th CIRP Conference on Electro Physical and Chemical Machining (ISEM2018)   ( 68 )   100 - 103   2018.4

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    Authorship:Lead author   Language:English   Publishing type:Research paper (international conference proceedings)  

    DOI: 10.1016/j.procir.2017.12.030

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  • Effects of pulse duration on removal characteristics of silver nanowire transparent conductive film by nanosecond pulsed laser Reviewed International journal

    Norio Nishi, Yasuhiro Okamoto, Masafumi Oshita, Akira Okada, Togo Shinonaga, Tomokazu Sakagawa

    JOURNAL OF MATERIALS PROCESSING TECHNOLOGY   240 ( 240 )   255 - 261   2017.2

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    Authorship:Corresponding author   Language:English   Publishing type:Research paper (scientific journal)   Publisher:ELSEVIER SCIENCE SA  

    In laser processing of silver nanowire transparent conductive film covered with an acrylic resin layer, effects of pulse duration on electrical insulation and surface quality were experimentally investigated by using nanosecond pulsed laser. The minimum laser fluence to achieve the stable electrical insulation by removal of silver nanowire became small with decreasing the pulse duration, but shorter pulse duration showed drastic change of removal trace area of silver nanowires at the boundary region of laser fluence to change conductive state to insulation one. In contrast, longer pulse duration around 200 ns indicated almost constant small removal trace area of silver nanowires, and wide processing window to perform the stable electrical insulation with small removal trace area of silver nanowires can be expected by using a proper long pulse duration in nanosecond pulsed laser processing. (C) 2016 Elsevier B.V. All rights reserved.

    DOI: 10.1016/j.jmatprotec.2016.10.004

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  • Characteristics of spatter in micro-drilling of metal sheet by pulsed Nd: YAG laser Reviewed

    Yasuhiro Okamoto, Hibiki Yamamoto, Akira Okada

    International Journal of Automation Technology   10 ( 6 )   874 - 881   2016.11

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    Authorship:Lead author, Corresponding author   Language:English   Publishing type:Research paper (scientific journal)   Publisher:Fuji Technology Press  

    In laser cutting and drilling process, molten material was scattered as spatter, which deteriorates the surface integrity of a workpiece because of the thermal damage. It is expected that the control of assist gas flow can reduce the adhesion of spatter. In order to investigate the improvement method of thermal damage due to the adhesion of spatter, it is required to clarify characteristics of spatter. Therefore, a method was developed to collect and analyze spatter based on the use of high-speed video cameras in the lasermicro-drilling process, and the characteristics of spatter movement were numerically investigated by CFD analysis. The scattering velocity and angle of the spatter were investigated by recognizing and tracking spatter with the high-speed video observation. The movement of spatter was observed by using two high-speed video cameras, and analyzed by using a two-direction tracking method, in which the 3D tracking lines of spatter particles were reconstructed in the forward and backward frames, and the actual trajectory of individual spatter particle was obtained by averaging those tracking lines. These measurements revealed that the initial velocity of spatter was mainly distributed from 52 m/s to 200 m/s with an average velocity of 129 m/s. The initial angle of spatter was mainly distributed between 0 and 30 degrees from the workpiece surface in the upward direction. There was little correlation between the initial velocity and angle of spatter. The diameter of spatter was mainly distributed from 1 µm to 4 µm with an average diameter of 3.7 µm. It is important to use the processing conditions achieving the smaller spatter diameter in order to reduce the thermal damage caused by spatter. Although coaxial assist gas flow has an influence on the spatter behavior, that time period is very short. Therefore, it is important to control the spatter behavior outside of the coaxial assist gas flow by using an additional gas flow to prevent the thermal damage to the workpiece surface.

    DOI: 10.20965/ijat.2016.p0874

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  • Mechanism of dynamic plasma motion in internal modification of glass by fs-laser pulses at high pulse repetition rate Reviewed

    Isamu Miyamoto, Yasuhiro Okamoto, Rie Tanabe, Yoshiro Ito, Kristian Cvecek, Michael Schmidt

    OPTICS EXPRESS   24 ( 22 )   25718 - 25731   2016.10

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    Authorship:Corresponding author   Language:English   Publishing type:Research paper (scientific journal)   Publisher:OPTICAL SOC AMER  

    Evolution of free-electron density in internal modification of glass by fs-laser pulses at high pulse repetition rates is simulated based on rate equation model, which is coupled with thermal conduction model in order to incorporate the effect of thermal ionization. Model shows that highly absorbing small plasma generated near the geometrical focus moves toward the laser source periodically to cover the region, which is much larger than focus volume. The simulated results agree qualitatively with dynamic motion of plasma produced in internal modification of borosilicate glass by fs-laser pulses at 1 MHz through the observation using high-speed video camera. The paper also reveals the physical mechanism of the internal modification of glass when heat accumulation is significant. (C) 2016 Optical Society of America

    DOI: 10.1364/OE.24.025718

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  • Formation of Internal Modified Line with High Aspect Ratio in Sapphire by Sub-nanosecond Pulsed Fiber Laser Reviewed

    Yasuhiro Okamoto, Tomohiro Takekuni, Akira Okada

    JOURNAL OF LASER MICRO NANOENGINEERING   9 ( 1 )   52 - 58   2014.3

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    Authorship:Lead author, Corresponding author   Language:English   Publishing type:Research paper (scientific journal)   Publisher:JAPAN LASER PROCESSING SOC  

    The internal modification technique for a sapphire substrate using a sub-nanosecond pulsed fiber laser of 180 ps was experimentally investigated with a normal achromatic focusing lens of 20 mm focal length, and the possibility of a singulation method with this internal modification technique was discussed. The laser beam of 1060 nm was focused in sapphire substrate of 0.4 mm thickness by passing through GaN epitaxial layer grown on the top surface of the sapphire substrate, and the internal modification zone was generated from the stain-finished surface as the bottom surface of sapphire substrate. The laser beam was absorbed from the stain-finished bottom surface, and the absorption point moved in the axis of laser irradiation without moving the focusing optics. The narrow internal modified line less than 5 mu m in width with a high aspect ratio of more than 30 was successfully obtained only by one laser scanning irradiation from the epitaxial layer side. A sapphire wafer could be broken from the internal modified line with less damage of the epitaxial layer by a stress sufficiently smaller than the tensile strength of sapphire. The breaking strength and its dispersion became smaller with increasing number of laser scans.

    DOI: 10.2961/jlmn.2014.01.0011

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  • Novel Micro-welding of Silicon and Glass by Ultrashort Pulsed Laser Reviewed

    Yasuhiro Okamoto, Isamu Miyamoto, Jorma Vihinen, Akira Okada

    Materials Science Forum   ( 783-786 )   2792 - 2797   2014

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    Authorship:Lead author, Corresponding author   Language:English   Publishing type:Research paper (scientific journal)  

    DOI: 10.4028/www.scientific.net/MSF.783-786.2792

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  • Evaluation of molten zone in micro-welding of glass by picosecond pulsed laser Reviewed

    Yasuhiro Okamoto, Isamu Miyamoto, Kristian Cvecek, Akira Okada, Kenta Takahashi, Michael Schmidt

    Journal of Laser Micro Nanoengineering   8 ( 1 )   65 - 69   2013.1

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    Authorship:Lead author, Corresponding author   Language:English   Publishing type:Research paper (scientific journal)  

    Glass materials have been widely used in optics, MEMS, electronics and biomedical applica-tions because of their excellent optical, mechanical and chemical properties. Fusion welding by ul-trashort pulsed laser has been proposed as a promising technique for glass joining, since joining can be accomplished without an intermediate layer and mechanical contact. However, to apply a fusion welding technique by ultrashort pulsed laser as a reliable joining method, it is important to under-stand the mechanical properties of the weld seam since glass materials are very sensitive to tempera-ture gradients. Therefore, a method of evaluating the weld seam in the fusion welding of glass by picosecond pulsed laser was discussed, and its mechanical strength was investigated. A larger opti-cal contact area had a great influence on the shear load of the weld seam, while a smaller optical contact area could reduce the influence of the contact area on the measurement of shear load. There-fore, it was important to reduce the optical contact area to accurately evaluate the shearing strength of weld seam. The mechanical strength of the weld seam reduced at a low pulse repetition rate. High bending strength and shear stress could be obtained at a proper pulse repetition rate.

    DOI: 10.2961/jlmn.2013.01.0013

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  • Influence of Polarization Plane on Groove Shape in Scribing of Sapphire by THG:YAG Laser

    International journal of electrical machining   ( 18 )   49 - 54   2013

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    Authorship:Lead author, Corresponding author   Language:English   Publisher:Japan Society of Electrical-Machining Engineers  

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  • Micro-Machining Characteristics of Ceramics by Harmonics of Nd:YAG laser Reviewed

    Yasuhiro Okamoto, Tomokazu Sakagawa, Hikaru Nakamura, Yoshiyuki Uno

    JOURNAL OF ADVANCED MECHANICAL DESIGN SYSTEMS AND MANUFACTURING   2 ( 4 )   661 - 667   2008

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    Authorship:Lead author, Corresponding author   Language:English   Publishing type:Research paper (scientific journal)   Publisher:JAPAN SOC MECHANICAL ENGINEERS  

    Aluminum nitride and silicon carbide are expected as a useful material for the substrate in semiconductor industry because of their excellent properties. Precision micro-machining without crack and with little heat affected zone is required for their applications. Shorter wavelength makes it possible to remove a material with little heat affected zone because of its high photon energy. Therefore, effects of wavelength on machining characteristics of AlN and SiC in micro-drilling using Q-swithched YAG harmonics were experimentally investigated. The drilled depth increased with decreasing the wavelength. Under the reduced pressure condition, the drilled depth increased, and the better surface integrity could be obtained compared to the atmospheric pressure condition. The circumference region around the drilled hole was oxidized for all the case, and the oxidization in the case of fourth harmonic was more remarkable than that in second harmonic. In the initial stage of drilling for AlN with fundamental wavelength, the irradiated point expanded by the absorption of laser beam with increasing the number of laser pulse, and the processing was carried out by crumbling the grain due to the thermal expansion. On the other hand, the higher harmonics could make a hole at the irradiated point from the initial stage without thermal expansion.

    DOI: 10.1299/jamdsm.2.661

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  • Evaluation of Machining Characteristics of Aluminum Nitride by Harmonics of Nd: YAG Laser : Effects of Laser Beam Wavelength on Machining Characteristics

    OKAMOTO Yasuhiro, KATAOKA Norio, UNO Yoshiyuki, NAKASHIBA Shin-ichi, TANINO Itaru

    Journal of the Japan Society for Precision Engineering. Supplement. Contributed papers   72 ( 6 )   725 - 729   2006

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    Language:Japanese   Publisher:The Japan Society for Precision Engineering  

    Machining characteristics of aluminum nitride by various kinds of the harmonics of Nd:YAG laser, that is the fundamental harmonic (λ_1=1064nm), the second harmonic (λ_2=532nm), the third harmonic (λ_3=355nm) and the forth harmonic (λ_4=266nm), were experimentally investigated. Since the material removal is mainly performed by thermal processing in the case of long wavelength such as fundamental wavelength, the removal rate greatly decreases with increasing the distance from the focusing point to the tip of removal. Thus, the limit of removal depth was shallow, since the material removal was sensitive to the energy density of laser beam. On the other hand, when the photon energy of laser beam is larger than the bonding energy of material, the material is mainly removed by the photochemical reaction. Thus, the decrease of removal rate was small for shorter wavelength. Therefore, the removal rate increases with decreasing the wavelength of laser beam for long term irradiation under the same energy condition. In the case of deep hole drilling, the drilled depth increases proportionally with the number of laser shot at the beginning region. Therefore, the removal depth could be controlled by the number of laser shot in this region.

    DOI: 10.2493/jspe.72.725

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    Other Link: https://jlc.jst.go.jp/DN/JALC/00386431733?from=CiNii

  • Effects of Laval Nozzle on Precision Micro Cutting of Thin Metal Plate by Pulsed YAG Laser

    岡本康寛, 宇野義幸, 村上義文, 細萱正義, 三柳直毅

    精密工学会誌   70 ( 3 )   433 - 437   2004.3

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    Language:Japanese   Publisher:The Japan Society for Precision Engineering  

    The stagnation pressure, which is the sum of static and dynamic pressures, has a great influence on machining performance in laser cutting. Therefore, increasing the velocity of assist gas is effective in reducing the height of dross. In this paper, Laval nozzle was newly designed, because it can increase the velocity of assist gas flow spouted from nozzle tip. Effects of Laval nozzle on assist gas flow and the machining results in precision cutting of thin metal plate by a pulsed YAG laser were experimentally investigated. Assist gas flow from Laval nozzle does not have Mach Shock Disk and goes more straight than a traditional convergent nozzle. Therefore, the pressure on a workpiece increases, since assist gas flow from Laval nozzle can utilize energy more efficiently. However, caution is necessary in setting the cylinder gas pressure, since Laval nozzle has many unstable regions, where the pressure on the workpiece changes periodically. Using Laval nozzle makes it possible to reduce the height of dross even under low cylinder gas pressure condition compared to convergent nozzle. Thus the consumption of flow quantity of assist gas can be reduced, when the same height of dross is desired. Moreover, it was pointed out that the convexed inner wall of nozzle leads to the reduction of dross generation and unstable region.

    DOI: 10.2493/jspe.70.433

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  • Investigation of Effective Gas Shielding Method for a Wide-area in Vertical-position Laser Welding of Titanium Reviewed International journal

    Yasuhiro Okamoto, Togo Shinonaga, Akira Okada

    International Journal of Electrical Machining   ( 29 )   20 - 29   2024.3

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    Authorship:Lead author, Last author, Corresponding author   Language:English   Publishing type:Research paper (scientific journal)  

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  • Application of large-area electron beam irradiation to micro-edge filleting Reviewed International journal

    Togo Shinonaga, Hibiki Tajima, Yasuhiro Okamoto, Akira Okada

    Journal of Manufacturing Processes   107   65 - 73   2023.12

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    Authorship:Corresponding author   Language:English   Publishing type:Research paper (scientific journal)   Publisher:Elsevier BV  

    DOI: 10.1016/j.jmapro.2023.10.039

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  • Fundamental Study on CO2 Laser Forming of Carbon Fiber Reinforced Thermoplastic Sheet-relationship between Pulse Waveform and Forming Characteristics Reviewed International journal

    Ryoji Kitada, Sena Kizaki, Yasuhiro Okamoto, Akira Okada

    Proceedings of 10th International Conference of Asian Society for Precision Engineering and Nanotechnology   ASPEN2023P_064   2023.11

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  • レーザピーニングのパルスエネルギー,スポット径及び オーバーラップ率が圧縮残留応力生成に及ぼす影響 Reviewed

    加藤智治, 崎野良比呂, 菅野恒太, 岡本康寛, 潘 豪, 梅津皓平

    鋼構造年次論文報告集   31   508 - 514   2023.11

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    Authorship:Corresponding author   Language:Japanese   Publishing type:Research paper (other academic)   Publisher:(一社)日本鋼構造協会  

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  • Fiber laser cutting of steel plate by twin spot beam setting in scanning direction Reviewed International journal

    Yasuhiro Okamoto, Kota Morimoto, Naoki Kai, Akira Okada, Hiroaki Ishiguro, Ryohei Ito, Hiroshi Okawa

    Journal of Laser Applications   35 ( 4 )   042049:1 - 042049:11   2023.10

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    This study investigated the effects of laser beam intensity distribution on the reduction of dross height in fiber laser cutting of a steel plate with 3.2 mm thickness. A twin-spot beam was produced by splitting a single Gaussian beam into two beams using a special axicon lens, and these beams were set in the scanning direction for cutting experiments. The power ratio of two beams (R:F = Rear power:Front power) was varied to discuss the intensity balance for the effective reduction of dross. After cutting experiments, ray tracing analysis was conducted using an optical analysis to calculate the absorbed power density distributions in the kerf. A smaller dross height of 18 μm can be achieved at a power ratio of R:F = 8:2, and its value is lower than that by a single Gaussian beam. At a power ratio of R:F = 8:2, the front beam of lower power is irradiated at the upper part of the workpiece, and the rear beam of higher power is absorbed at the lower part of the workpiece. Thus, effective heat input to the lower part of the workpiece can contribute to a reduction of the dross height. Variation of power ratio in the rear and the front beams is effective in controlling the cutting front shape, and the uniformity of absorbed power in the thickness direction can be improved by setting the rear beam of about four times higher power to the front beam of lower power to obtain a smaller dross height in the case of a 3.2 mm steel plate.

    DOI: 10.2351/7.0001097

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  • Fundamental study on high-quality welding of copper and aluminum by angled and superposed irradiation of blue and near-infrared lasers Reviewed International journal

    Yuki Yamada, Yasuhiro Okamoto, Akira Okada, Norio Nishi, Takeshi Yamamura, Katsutoshi Nagasaki, Kazunobu Mameno

    Journal of Laser Applications   35 ( 4 )   042005:1 - 042005:9   2023.9

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    In order to achieve sustainable development goals, decarbonization and low-carbonization are required. Electric and hybrid vehicles are indispensable for the conservation of natural environment, and the lightweight construction and the effective transfer of electricity become important. Thus, copper and aluminum have been increasingly recognized as important materials because of their excellent materials’ properties. However, in the welding of these materials, it is difficult to obtain strong joints because there are problems in the brittle intermetallic compounds and the welding defects due to different melting points between copper and aluminum. Especially in the joining of copper and aluminum by copper side irradiation, aluminum-rich intermetallic compounds (IMCs) of brittle state result in the decrease of mechanical strength. Therefore, mild heat input from copper to aluminum would be necessary to reduce the brittle IMC. Angled irradiation might result in the mild energy input to aluminum because it can be expected that aluminum would be heated by the reflected light inside the keyhole generated in copper according to its high light reflection. In addition, stable welding can be expected by the superposed irradiation of blue and near-infrared lasers because of high light absorption rate of blue laser to copper. The angled and the superposed irradiation could achieve a stable welding state, and the generation of aluminum-rich IMC becomes smaller. Angled irradiation of a near-infrared laser showed equivalent joining strength to the superposed irradiation of two wavelengths, and the combination of angled and superposed irradiation achieved a remarkable increase of joining strength in a cross tensile test by 80%.

    DOI: 10.2351/7.0001096

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  • Study on joint characteristics in laser butt welding of AMed and wrought Ti6Al4V plates Invited Reviewed International coauthorship International journal

    Yasuhiro Okamoto, Togo Shinonaga, Yoshito Takemoto, Akira Okada, Akihiro Ochi, Ryuya Kishimoto, Sisa Pityana, Nana Arthur, Peter Omoniyi, Rasheedat Mahamood, Martin Maina, Esther Akinlabi

    Welding in the World   67 ( 5 )   1997 - 2005   2023.6

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    Titanium alloy Ti6Al4V has been widely applied to medical, automotive, and aerospace industries due to its excellent properties such as high strength and excellent corrosion resistance. On the other hand, additive manufacturing (AM) technology can give the freedom of design of the products. In order to spread the AMed products, the joining of AMed and wrought products are required, and it is important to understand the joint characteristics. In this study, butt welding of Ti6Al4V plate was conducted by fiber laser in argon shielding, and the joint characteristics of laser weld wrought/wrought, AMed/AMed, and AMed/wrought Ti6Al4V plates were experimentally investigated. The AMed plate has higher tensile strength than wrought plate but the elongation of AMed plate is smaller, since AMed plate has α’ martensite due to rapid cooling during laser irradiation in AM process. Then, the laser weld joint of AMed/AMed plates has higher tensile strength, but smaller elongation than that of wrought/wrought plates. The weld joint of AMed/wrought plates shows good welding state, since small heat input leads to formation of small weld bead with higher hardness between wrought and AMed plates.

    DOI: 10.1007/s40194-023-01533-3

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    Other Link: https://link.springer.com/article/10.1007/s40194-023-01533-3/fulltext.html

  • Investigation on Laser Welding of Copper and Aluminum by Irradiation from Copper-side Invited Reviewed International journal

    Yasuhiro Okamoto, Yuki Yamada, Akihiro Ochi, Takeshi Yamamura, Katsutoshi Nagasaki, Kazunobu Mameno, Norio Nishi, Akira Okada

    Proceedings of Laser in Manufacturing 2023   2023.6

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  • Effect of scanning speed on molten metal behaviour under angled irradiation with a continuous-wave laser Reviewed International journal

    Tatsuhiko Sakai, Yasuhiro Okamoto, Nozomi Taura, Riku Saito, Akira Okada

    Journal of Materials Processing Technology   313   117866 - 117866   2023.4

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    Authorship:Last author, Corresponding author   Language:English   Publishing type:Research paper (scientific journal)   Publisher:Elsevier BV  

    DOI: 10.1016/j.jmatprotec.2023.117866

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  • Fundamental Study on Laser Forming of Carbon Fiber Reinforced Thermoplastic Sheet with Low Surface Damage by Using Pulsed CO2 Laser Reviewed International journal

    Ryoji KITADA, Rina WATANABE, Yasuhiro OKAMOTO, Akira OKADA, Sena KIZAKI

    Proceedings of 19th International Conference on Precision Engineering   C090   2022.11

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  • Influence of Focusing Position on Micro-groove Formation on Metal Surface by High-speed Scanning of Angled CW Laser Irradiation Reviewed International journal

    Riku Saito, Yasuhiro Okamoto, Akira Okada, Tatsuhiko Sakai

    Proceedings of 19th International Conference on Precision Engineering   2022.11

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  • Fabrication of High-quality Micro-shape on Monocrystalline Diamond Surface by Nanosecond Pulsed Laser and Acid Cleaning Reviewed International journal

    Tsubasa Okubo, Yasuhiro Okamoto, Akira Okada

    Proceedings of 4th International Conference on Machining, Materials and Mechanical Technologies IC3MT2022   C099   2022.10

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  • Fiber laser cutting of steel materials with twin spot beam-twin spot setting in kerf width direction Reviewed International journal

    Kota Morimoto, Atsushi Yagi, Naoto Kai, Yasuhiro Okamoto, Akira Okada, Hiroaki Ishiguro, Ryohei Ito, Akihiko Sugiyama, Hiroshi Okawa

    Journal of Laser Applications   34   042009-1 - 042009-7   2022.9

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    DOI: 10.2351/7.0000740

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  • Study on Joint Characteristics in Laser Butt Welding of AMed and Bulk Ti6Al4V plates Reviewed International coauthorship International journal

    Yasuhiro Okamoto, Togo Shinonaga, Yoshito Takemoto, Akira Okada, Akihiro Ochi, Ryuya Kishimoto, Sisa Pityana, Nana Arthur, Peter Omoniyi, Rasheedat Mahamood, Martin Maina, Esther Akinlabi

    Proceedings of IIW 2022 International Conference on Welding and Joining   469 - 472   2022.7

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  • High-quality Micro-shape Fabrication of Monocrystalline Diamond by Nanosecond Pulsed Laser and Acid Cleaning Invited Reviewed International journal

    Yasuhiro Okamoto, Tsubasa Okubo, Atsushi Kajitani, Akira Okada

    International Journal of Extreme Manufacturing   ( 4 )   025301   2022.3

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    The flat plane of small surface roughness below 0.1 µm average roughness could be obtained for monocrystalline diamond by nanosecond pulsed laser irradiation of 1060 nm and post-process of acid cleaning, at the laser fluence around the threshold value of material removal. The glossy and flat plane at the bottom of micro-groove was parallel to the top surface of specimen, although the round beam of Gaussian-mode was irradiated in the direction perpendicular to the top surface of specimen. The square beam of top-hat mode could obtain shallower micro-groove with wide flat bottom in comparison with the round beam of Gaussian mode, and then the creation method of flat plane with small surface roughness was discussed in the arrangement strategy of linear micro-grooving by the square beam of top-hat mode. Normal side-by-side repetition of linear micro-grooving could not create the flat plane of a constant depth. Therefore, two-step scanning method was proposed in order to overcome the problem in the normal side-by-side repetition of liner micro-grooving. Non-removal areas were partly retained between the processing lines in the first step, and the laser scanning was conducted on the retained area in the second step. Newly proposed two-step scanning method was practical and useful to create a wide flat plane with small surface roughness, and the controllability of micro-groove depth could be improved by the two-step scanning method. This proposed method can reduce the surface roughness in addition to the shape creation of monocrystalline diamond, and it can be used as the high-quality micro-shape fabrication method of monocrystalline diamond.

    DOI: 10.1088/2631-7990/ac5a6a

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  • Joint integrity evaluation of laser beam welded additive manufactured Ti6Al4V sheets Reviewed International coauthorship International journal

    P. O. Omoniyi, R. M. Mahamood, N. Arthur, S. Pityana, S. Skhosane, Y. Okamoto, T. Shinonaga, M. R. Maina, T. C. Jen, E. T. Akinlabi

    Scientific Reports   12 ( 12 )   4602   2022.3

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    <title>Abstract</title>The feasibility of joining laser metal deposited Ti6Al4V sheets using laser beam welding was investigated in this article. The additive manufactured sheets were joined using a 3 kW CW YLS-2000-TR ytterbium laser system. The mechanical properties and microstructure of the welded additive manufactured parts (AM welds) were compared with those of the wrought sheets welded using the same laser process. The welds were characterized and compared in terms of bead geometry, microhardness, tensile strength, fractography, and microstructure. The differences in characteristics are majorly found in the width of the bead and tensile strength. The bead width of AM welds appear wider than the wrought welds, and the wrought welds exhibited higher tensile strength and ductility than the AM welds.

    DOI: 10.1038/s41598-022-08122-2

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    Other Link: https://www.nature.com/articles/s41598-022-08122-2

  • Study on Laser Drilling Process of Solid Metal on Its Liquid Reviewed International journal

    Yasuhiro Okamoto, Nozomi Taura, Akira Okada

    International Journal of Electrical Machining   27   35 - 39   2022.3

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    DOI: 10.2526/ijem.27.35

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  • Fundamental Investigation of Working fluid Flow Formed by High-speed Wire Running in Multi-wire EDM Slicing Reviewed

    Shusei TABUCHI, Yasuhiro OKAMOTO, Akira OKADA, Haruya KURIHARA

    Proceedings of the 10th International Conference on Leading Edge Manufacturing in 21st Century   517 - 518   2021.11

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  • Fundamental Study on Laser Micro-welding of Glass by Using Spatial Light Modulator Reviewed

    Kazuki IHORIYA, Yasuhiro OKAMOTO, Akira OKADA

    Proceedings of the 10th International Conference on Leading Edge Manufacturing in 21st Century   341 - 342   2021.11

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  • Fundamental Study on Laser Forming Characteristics of Carbon Fiber Reinforced Thermoplastic Sheet Reviewed

    Ryoji KITADA, Rina WATANABE, Takashi KAWAZOE, Yasuhiro OKAMOTO, Akira OKADA

    Proceedings of the 10th International Conference on Leading Edge Manufacturing in 21st Century   349 - 350   2021.11

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  • Fundamental Study on Surface Texturing of Alloy Steel by Ultrashort Pulsed Laser for Control of Water Repellency Reviewed

    Kentaro MURATA, Togo SHINONAGA, Yasuhiro OKAMOTO, Akira OKADA

    Proceedings of the 10th International Conference on Leading Edge Manufacturing in 21st Century   347 - 348   2021.11

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  • Fundamental Study on Calcination Method of Limestone by Using CW Laser of Near-infrared Reviewed

    Takafumi MIYAJIMA, Yasuhiro OKAMOTO, Shuji FUJIKI, Masakazu OKA, Shunjirou SHIZUKA, Akira OKADA

    Proceedings of the 10th International Conference on Leading Edge Manufacturing in 21st Century   345 - 346   2021.11

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  • Formation and Its Mechanism of High-speed Micro-grooving on Metal Surface by Angled CW Laser Irradiation Reviewed

    Nozomi Taura, Akiya Mitsunobu, Tatsuhiko Sakai, Yasuhiro Okamoto, Akira Okada

    Journal of Laser Micro/Nanoengineering   16 ( 2 )   109 - 114   2021.10

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    Authorship:Last author, Corresponding author   Language:English   Publishing type:Research paper (scientific journal)   Publisher:Japan Laser Processing Society  

    DOI: 10.2961/jlmn.2008.02.0007

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  • Investigation and optimization of heat treatment process on tensile behaviour of Ti6Al4V alloy Reviewed International coauthorship International journal

    P.O. Omoniyi, R.M. Mahamood, N. Arthur, S. Pityana, S.A. Akinlabi, Y. Okamoto, M.R. Maina, E.T. Akinlabi

    Materialwissenschaft und Werkstofftechnik   52 ( 10 )   1057 - 1063   2021.10

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    Authorship:Last author   Language:English   Publishing type:Research paper (scientific journal)   Publisher:Wiley  

    DOI: 10.1002/mawe.202000314

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    Other Link: https://onlinelibrary.wiley.com/doi/full-xml/10.1002/mawe.202000314

  • Laser Butt Welding of Thin Ti6Al4V Sheets: Effects of Welding Parameters Reviewed International coauthorship International journal

    Peter Omoniyi, Rasheedat Mahamood, Nana Arthur, Sisa Pityana, Samuel Skhosane, Yasuhiro Okamoto, Togo Shinonaga, Martin Maina, Tien-Chien Jen, Esther Akinlabi

    Journal of Composites Science   5 ( 9 )   246 - 246   2021.9

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    Titanium and its alloys, particularly Ti6Al4V, which is widely utilized in the marine and aerospace industries, have played a vital role in different manufacturing industries. An efficient and cost-effective way of joining this metal is by laser welding. The effect of laser power and welding speed on the tensile, microhardness, and microstructure of Ti6Al4V alloy is investigated in this paper. Results show that the microhardness is highest at the fusion zone and reduces towards the base metal. The microstructure at the fusion zone shows a transformed needle-like lamellar α phase, with a martensitic α’ phase observed within the heat affected zone. Results of tensile tests show an improved tensile strength compared to the base metal.

    DOI: 10.3390/jcs5090246

    Web of Science

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  • Influence of Free-electron Density Distribution on Mechanical Strength in Micro-welding of Glass by Picosecond Pulsed Laser Reviewed

    Zhiyong Ouyang, Yasuhiro Okamoto, Kazuki Ihoriya, Akira Okada

    Journal of Smart Processing   10 ( 5 )   294 - 300   2021.9

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  • Investigation on reduction of dross height by analyzing beam intensity distribution in fiber laser cutting Reviewed International journal

    Naoto Kai, Yasuhiro Okamoto, Akira Okada, Hiroaki Ishiguro, Ryohei Ito, Akihiko Sugiyama, Hiroshi Okawa, Rio Fujita

    Journal of Laser Applications   33 ( 4 )   109 - 114   2021.9

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    DOI: 10.2351/7.0000470

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  • Formation of Smooth and Flat Area for Monocrystalline Diamond by ns Pulsed Laser Reviewed

    Yasuhiro Okamoto, Tsubasa Okubo, Atsuya Kajitani, Akira Okada

    Proceedings of Laser in Manufacturing 2021   On-line   2021.6

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  • Surface smoothing and repairing of additively manufactured metal products by large-area electron beam irradiation Reviewed International journal

    T. Shinonaga, A. Yamaguchi, Y. Okamoto, A. Okada

    CIRP Annals   70 ( 1 )   143 - 146   2021.5

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    DOI: 10.1016/j.cirp.2021.04.063

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  • Reliable and strong micro-welding of glass by ultrashort pulsed laser Invited Reviewed International journal

    Yasuhiro Okamoto, Zhiyong Ouyang, Akira Okada

    Proceedings of SPIE   11676   116760P-1 - 116760P-7   2021.3

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    Authorship:Lead author, Corresponding author   Language:English   Publishing type:Research paper (international conference proceedings)   Publisher:SPIE  

    DOI: 10.1117/12.2584895

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  • Reliable and strong micro-welding of glass by ultrashort pulsed laser Invited Reviewed

    Yasuhiro Okamoto, Zhiyong Ouyang, Akira Okada

    Proceedings of Frontiers in Ultrafast Optics: Biomedical, Scientific, and Industrial Applications XXI, Lasers and Application in Science and Engineering, Photonics West Conference 2021   11676 ( 0 )   116760P-1 - 116760P-7   2021.3

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    Authorship:Lead author   Language:English   Publishing type:Research paper (international conference proceedings)  

    DOI: https://doi.org/10.1117/12.2584895

  • Surface Profile Variation of Periodic Surface Nanostructures Produced by Ultrashort Pulsed Laser for Enhancement of Cell Orientation Reviewed

    Togo Shinonaga, Shouno Kinoshita, Yasuhiro Okamoto, Akira Okada

    International Journal of Electrical Machining   26   54 - 54   2021.3

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    Authorship:Corresponding author   Language:English   Publishing type:Research paper (scientific journal)   Publisher:Japan Society of Electrical Machining Engineers  

    DOI: 10.2526/ijem.26.54

    J-GLOBAL

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  • Fundamental study on reduction of dross in fiber laser cutting of steel by shifting nozzle axis Reviewed

    Atsushi Yagi, Seigo Kadonaga, Yasuhiro Okamoto, Hiroaki Ishiguro, Ryohei Ito, Akihiko Sugiyama, Hiroshi Okawa, Rio Fujita, Akira Okada

    Journal of Laser Applications   33 ( 1 )   012022 - 012022   2021.2

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    DOI: 10.2351/7.0000300

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  • High-Speed Micro-Grooving of Metal by Angled Irradiation of Single-Mode CW Fiber Laser Reviewed International journal

    Tatsuhiko Sakai, Yasuhiro Okamoto, Chie Katayama, Hirofumi Imai, Akira Okada

    Applied Sciences   10 ( 23 )   8333-1 - 8333-11   2020.11

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    Laser micro-grooving has excellent potential to improve the surface properties of metals. In this study, high-speed micro-grooving of the surfaces of mild steel SS400 and aluminum alloy A1050 was investigated using a single-mode continuous-wave fiber laser with an average power of 200 W. Experiments were conducted at laser beam scanning speeds of 1 to 6 m/s. The incident angle of the laser beam in the plane perpendicular to the scanning axis was varied from 0 to 60°. A relatively deep groove (approximately 30 µm in depth) and a high upheaval (10 µm in height) were formed along the scanning line at an incident angle of 45° on the SS400, whereas only shallow grooves were formed on A1050. The micro-groove formation mechanism was discussed on the basis of high-speed camera observation, groove shapes, and the thermophysical properties of the metal. Asymmetric molten metal flow and solidification around the keyhole are thought to play important roles in micro-groove formation. Although the laser irradiation conditions must be optimized according to the thermophysical properties of the material, angled laser irradiation has the potential to effectively form micro-grooves.

    DOI: 10.3390/app10238333

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  • Development of Control Method by Variation Range of Gap Voltage in Multi-wire EDM Slicing with Group Power Supplying Reviewed

    Tomoya Takegawa, Shusei Tabuchi, Yasuhiro Okamoto, Akira Okada, Haruya Kurihara

    Proceedings of 18th International Conference on Precision Engineering   126 - 127   2020.11

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  • Micro-welding Characteristics of Glass Plates with Gap by Picosecond Pulsed Laser Reviewed

    Fujiwara Takumi, Zhiyong Ouyang, Yasuhiro Okamoto, Akira Okada

    Proceedings of 18th International Conference on Precision Engineering   164 - 165   2020.11

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  • Study on High-efficiency and High-quality Micro-welding of Copper by Superposition of 532 nm and 1064 nm Lasers Reviewed International coauthorship

    Shota Kawasaki, Yasuhiro Okamoto, Martin Ruthandi Maina, Akira Okada, Shin -ichi Nakashibaichi, Norio Nishi

    Proceedings of 18th International Conference on Precision Engineering   166 - 167   2020.11

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  • Investigation of the Mechanical and Microstructural Properties of TIG Welded Ti6Al4V Alloy Reviewed International coauthorship International journal

    P. O. Omoniyi, R. M. Mahamood, N. Arthur, S. Pityana, S. A. Akinlabi, S. Hassan, Y. Okamoto, M. R. Maina, E. T. Akinlabi

    Proceedings of 6th International Conference on Mechanical, Manufacturing and Plant Engineering   On-line   2020.11

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  • Fundamental Study on High-Speed Surface Processing of Metal by Angled Irradiation of Single-Mode CW Fiber Laser Reviewed

    Tatsuhiko Sakai, Chie Katayama, HIrofumi Imai, Yasuhiko Okamoto, Akira Okada

    Proceedings of 39th International Congress on Applications of Lasers & Electro-Optics 2020   On-line   2020.10

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  • Clarification of Temperature Distribution for Metals with Different Thermal Conductivity in Large-area Electron Beam Irradiation Reviewed International journal

    Shoya Ota, Tsubasa Sakai, Togo Shinonaga, Yasuhiro Okamoto, Akira Okada

    Procedia CIRP   95   960 - 965   2020.2

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    High energy density of electron beam (EB) with diameter of about 60 mm is obtained in a large-area EB irradiation method. This method can be used for melting and evaporating material surface instantly, and highly efficient surface finishing of metals such as mold steels and biomaterials is possible. Furthermore, surface functions such as corrosion resistance, water repellency and wear resistance can be improved since a thin modified layer with fine microstructure is formed on the EB irradiated surface. It is expected that thick modified layer is effective to maintain their surface functions for long-term. However, the material surface is slightly removed in formation of modified layer. Therefore, control and prediction of removal and modified layer thickness are important in order to obtain appropriate modified layer thickness and to keep the shape accuracy for metals with different thermal properties. In order to predict the removal and modified layer thickness, it is necessary to clarify the temperature distribution in depth direction and its time variation in large-area EB irradiation. In this study, changes of removal and modified layer thickness on metal workpiece with different thermal conductivity are investigated by calculation of temperature distribution in large-area EB irradiation. It is made clear that the modified layer thickness of workpiece with low thermal conductivity is larger than that with high one, while the removal layer thickness is almost the same regardless of thermal conductivity. Furthermore, analytical removal and modified layer thickness obtained by our unsteady heat conduction analysis agree well with the experimental ones. Therefore, our unsteady heat conduction analysis model has high accuracy, and it is possible to predict variations of removal and modified layer thickness on workpiece with different thermal conductivity.

    DOI: 10.1016/j.procir.2020.02.280

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  • Investigation on Surface Smoothing of Mold Material by Pulsed Laser Irradiation of 532 nm Reviewed International journal

    Kohei Umezu, Takuro Kozaki, Yasuhiro Okamoto, Akira Okada

    Procedia CIRP   95   879 - 884   2020.2

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    DOI: 10.1016/j.procir.2020.02.283

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  • Fundamental Investigation on Reduction of Surface Roughness for Mold Material by μs Pulsed Laser of 532 nm Reviewed

    Takuro Kozaki, Yasuhiro Okamoto, Akira Okada

    Proceedings of 8th International Conference of Asian Society for Precision Engineering and Nanotechnology   in USB   2019.11

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  • Investigation on Laser Drilling Process of Solid Metal on Its Liquid and Detection Method of Penetration State Reviewed

    Chikako Kawasaki, Yasuhiro Okamoto, Nozomi Taura, Tatsuhiko Sakai, Akira Okada

    Proceedings of 8th International Conference of Asian Society for Precision Engineering and Nanotechnology   in USB   2019.11

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  • Influence of Initial Surface State on Shape Change of LIPSS Reviewed

    Yuki Wada, Togo Shinonaga, Yasuhiro Okamoto, Akira Okada

    Proceedings of 8th International Conference of Asian Society for Precision Engineering and Nanotechnology   in USB   2019.11

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  • Investigation of Micro-grooving of Metals by High-speed Scanning of CW Laser Reviewed

    Chie Katayama, Yasuhiro Okamoto, Tatsuhiko Sakai, Seigo Kadonaga, Akira Okada

    Proceedings of 8th International Conference of Asian Society for Precision Engineering and Nanotechnology   in USB   2019.11

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  • Effective Supplying Method of Shielding Gas in Vertical-position Laser Welding of Pure Titanium Reviewed

    Yasuhiro Okamoto, Kyo Kitagawa, Seigo Kadonaga, Akira Okada, Esther T. Akinlabi, Sisa Pityana

    Proceedings of 38th International Congress on Applications of Lasers & Electro-Optics 2019   On-line   2019.10

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  • Laser Metal Deposition of Titanium Alloy (Ti6Al4V): A Review Reviewed International coauthorship International journal

    Esther T. Akinlabi, Yasuhiro Okamoto, Martin Ruthandi Maina, Stephen A. Akinlabi, Sisa Pityana, Monnamme Tlotleng, Ganiyat A. Soliu, Rasheedat M. Mahamood

    2019 International Conference on Engineering, Science, and Industrial Applications (ICESI)   2019.8

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    DOI: 10.1109/icesi.2019.8863018

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  • Wear Resistance Behaviour of Laser Additive Manufacture Materials: An Overview Reviewed International coauthorship International journal

    Rasheedat M. Mahamood, Yasuhiro Okamoto, Martin Ruthandi Maina, Stephen A. Akinlabi, Sisa Pityana, Monnamme Tlotleng, Esther T. Akinlabi

    2019 International Conference on Engineering, Science, and Industrial Applications (ICESI)   2019.8

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    DOI: 10.1109/icesi.2019.8863016

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  • Creation of Smooth and Flat Surface in Micro-machining of Monocrystalline Diamond by Pulsed Laser Reviewed

    Yasuhiro Okamoto, Takahiro Shimose, Atsuya Kajitani, Akira Okada

    Proceedings of Laser in Manufacturing 2019   in USB   2019.6

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  • Influence of Numerical Aperture on Molten Area Formation in Fusion Micro-Welding of Glass by Picosecond Pulsed Laser Reviewed

    Ouyang Zhiyong, Okamoto Yasuhiro, Ogino Yuta, Sakagawa Tomokazu, Okada Akira

    APPLIED SCIENCES-BASEL   9 ( 7 )   2019.4

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    DOI: 10.3390/app9071412

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  • Investigation of Separation Method for Gallium Nitride with Internal Modified Layer by Ultrashort Pulsed Laser Reviewed

    Yasuhiro Okamoto, Motoki Ota, Akira Okada

    International Journal of Electrical Machining   24   21 - 26   2019.3

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    DOI: 10.2526/ijem.24.21

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  • Improvement of Shape Accuracy in Multi-wire EDM Slicing of Semiconductor Ingot Reviewed

    Takayuki Ikeda, Yasuhiro Okamoto, Haruya Kurihara, Akira Okada, Masataka Kido

    Proceedings of the 17th International Conference on Precision Engineering (ICPE2018)   B-5-18   2018.11

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  • Improvement of Shape Accuracy in Multi-wire EDM Slicing of Semiconductor Ingot Reviewed

    Takayuki Ikeda, Yasuhiro Okamoto, Haruya Kurihara, Akira Okada, Masataka Kido

    Proceedings of the 17th International Conference on Precision Engineering (ICPE2018)   B-5-18   2018.11

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  • Effects of Concave Shape on Absorption Rate and Molten Volume in Micro-welding of Copper by Pulsed Nd:YAG Laser Reviewed

    Kazuki Hamada, Martin Maina, Reiki Inoue, Yasuhiro Okamoto, Akira Okada, Norio Nishi, Shin-ichi Nakashiba, Tomokazu Sakagawa

    Proceedings of the 17th International Conference on Precision Engineering (ICPE2018)   B-6-2   2018.11

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  • Effects of Concave Shape on Absorption Rate and Molten Volume in Micro-welding of Copper by Pulsed Nd:YAG Laser Reviewed

    Kazuki Hamada, Martin Maina, Reiki Inoue, Yasuhiro Okamoto, Akira Okada, Norio Nishi, Shin-ichi Nakashiba, Tomokazu Sakagawa

    Proceedings of the 17th International Conference on Precision Engineering (ICPE2018)   B-6-2   2018.11

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  • Improvement of Slope Angle of Kerf in Thick Plate Cutting of Mild Steel by Fiber Laser Reviewed

    Kyo Kitagawa, Yasuhiro Okamoto, Akira Okada, Hiroaki Ishiguro, Akihiko Sugiyama, Hironobu Miyoshi, Ryohei Ito

    Proceedings of 37th International Congress on Applications of Lasers & Electro-Optics 2018   on-line   2018.10

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  • Investigation of Assist Gas Flow to Improve Slope Angle of Kerf in Thick Plate Cutting of Mild Steel by Fiber Laser Reviewed

    Kyo Kitagawa, Yasuhiro Okamoto, Akira Okada, Hiroaki Ishiguro, Akihiko Sugiyama, Hironobu Miyoshi, Ryohei Ito

    Proceedings of 37th International Congress on Applications of Lasers & Electro-Optics 2018   on-line   2018.10

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  • Effects of polarization direction on removal characteristics of silver nanowire transparent conductive film by ultrashort pulsed laser Reviewed

    Shimose Takahiro, Okamoto Yasuhiro, Oshita Masafumi, Nishi Norio, Shinonaga Togo, Okada Akira

    JOURNAL OF ADVANCED MECHANICAL DESIGN SYSTEMS AND MANUFACTURING   12 ( 5 )   JAMDSM0100 - JAMDSM0100   2018.10

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    DOI: 10.1299/jamdsm.2018jamdsm0100

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  • Improvement of Slope Angle of Kerf in Thick Plate Cutting of Mild Steel by Fiber Laser Reviewed

    Kyo Kitagawa, Yasuhiro Okamoto, Akira Okada, Hiroaki Ishiguro, Akihiko Sugiyama, Hironobu Miyoshi, Ryohei Ito

    Proceedings of 37th International Congress on Applications of Lasers & Electro-Optics 2018   P115   2018.10

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  • Investigation of Assist Gas Flow to Improve Slope Angle of Kerf in Thick Plate Cutting of Mild Steel by Fiber Laser Reviewed

    Kyo Kitagawa, Yasuhiro Okamoto, Akira Okada, Hiroaki Ishiguro, Akihiko Sugiyama, Hironobu Miyoshi, Ryohei Ito

    Proceedings of 37th International Congress on Applications of Lasers & Electro-Optics 2018   M1305   2018.10

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  • Fundamental Study on Curved Hole by EDM Drilling Using a Suspended Ball Electrode into Practical Materials Reviewed

    Kohei Ota, Shuoxun Li, Akira Okada, Yasuhiro Okamoto, Atsushi Yamaguchi

    Proceedings of 2018 International Conference on Machining, Materials and Mechanical Technologies   283 - 287   2018.9

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  • High-speed Wire EDM by Newly Developed Copper-Zirconium Wire Electrode Reviewed

    Ayaka Kuwada, Naokuni Muramatsu, Kazuhiro Nomura, Yasuhiro Okamoto, Akira Okada

    Proceedings of 2018 International Conference on Machining, Materials and Mechanical Technologies   185 - 189   2018.9

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  • Influence of Molten Area on Joining Strength in Micro-welding of Glass by Picosecond Pulsed Laser Reviewed

    Yuta Ogino, Zhiyong Ouyang, Yasuhiro Okamoto, Togo Shinonaga, Akira Okada

    Proceedings of 2018 International Conference on Machining, Materials and Mechanical Technologies   194 - 198   2018.9

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  • High-speed Wire EDM by Newly Developed Copper-Zirconium Wire Electrode Reviewed

    Ayaka Kuwada, Naokuni Muramatsu, Kazuhiro Nomura, Yasuhiro Okamoto, Akira Okada

    Proceedings of 2018 International Conference on Machining, Materials and Mechanical Technologies   185 - 189   2018.9

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  • Fundamental Study on Curved Hole by EDM Drilling Using a Suspended Ball Electrode into Practical Materials Reviewed

    Kohei Ota, Shuoxun Li, Akira Okada, Yasuhiro Okamoto, Atsushi Yamaguchi

    Proceedings of 2018 International Conference on Machining, Materials and Mechanical Technologies   283 - 287   2018.9

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  • Influence of Molten Area on Joining Strength in Micro-welding of Glass by Picosecond Pulsed Laser Reviewed

    Yuta Ogino, Zhiyong Ouyang, Yasuhiro Okamoto, Togo Shinonaga, Akira Okada

    Proceedings of 2018 International Conference on Machining, Materials and Mechanical Technologies   194 - 198   2018.9

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  • Influence of Jet Flushing on Corner Shape Accuracy in Wire EDM Reviewed

    Tomonori Ebisu, Akiyoshi Kawata, Yasuhiro Okamoto, Akira Okada, Haruya Kurihar

    Procedia CIRP, Proceedings of 19th CIRP Conference on Electro Physical and Chemical Machining (ISEM2018)   68   104 - 108   2018.4

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  • Control of Kerf Width in Multi-wire EDM Slicing of Semiconductors with Circular Section Reviewed

    Yasuhiro Okamoto, Takayuki Ikeda, Haruya Kurihara, Akira Okada, Masataka Kido

    Procedia CIRP, Proceedings of 19th CIRP Conference on Electro Physical and Chemical Machining (ISEM2018)   68   100 - 103   2018.4

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  • High Surface Quality Welding of Aluminum Using Adjustable Ring-mode Fiber Laser Reviewed

    Martin Ruthandi Maina, Yasuhiro Okamoto, Akira Okada, Matti Närhi, Jarno Kangastupa, Jorma Vihinen

    Journal of Materials Processing Technology   258 ( 8 )   180 - 184   2018.4

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  • Influence of Jet Flushing on Corner Shape Accuracy in Wire EDM Reviewed

    Tomonori Ebisu, Akiyoshi Kawata, Yasuhiro Okamoto, Akira Okada, Haruya Kurihar

    Procedia CIRP, Proceedings of 19th CIRP Conference on Electro Physical and Chemical Machining (ISEM2018)   ( 68 )   104 - 108   2018.4

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    DOI: 10.1016/j.procir.2017.12.031

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  • Influence of Pulse Duration on Effective Energy on Material Removal in Micro-processing of Mild Steel by Several Hundred Nanoseconds Pulsed Laser Reviewed

    Yasuhiro Okamoto, Mizuna ITO, Akira Okada, Togo Shinonaga

    International Journal of Electrical Machining   23   38 - 44   2018.3

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    DOI: 10.2526/ijem.23.38

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  • Effects of Polarization Direction on Removal Characteristics of Silver Nanowire Transparent Conductive Film by fs Pulsed Laser Reviewed

    Takahiro SHIMOSE, Yasuhiro OKAMOTO, Masafumi OSHITA, Norio NISHI, Togo SHINONAGA, Akira OKADA

    Proceedings of the 9th International Conference on Leading Edge Manufacturing in 21st Century   2017.11

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  • Study on Shape Variation of Periodic Surface Nanostructures Produced with Ultrashort Pulse Laser for Control of Cell Spreading Direction Reviewed

    Shono KINOSHITA, Togo SHINONAGA, Yasuhiro OKAMOTO, Akira OKADA

    Proceedings of the 9th International Conference on Leading Edge Manufacturing in 21st Century   2017.11

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  • Influence of Pulse Duration on Effective Energy to Material in Nanosecond Pulsed Laser Processing of Mild Steel Reviewed

    Mizuna ITO, Shogo SHINONAGA, Yasuhiro OKAMOTO, Akira OKADA

    Proceedings of the 9th International Conference on Leading Edge Manufacturing in 21st Century   2017.11

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  • Low-visibility Processing of Silver Nanowire Transparent Conductive Film by Pulsed Laser Reviewed

    Yasuhiro Okamoto, Norio Nishi, Masafumi Oshita Takahiro Shimose,Togo Shinonaga,Akira Okada, Tomokazu Sakagawa

    Proceedings of 36th International Congress on Applications of Lasers & Electro-Optics 2017   On-line   2017.10

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  • Influence of Nozzle Jet Flushing on Wire Breakage in 1st-Cut Wire EDM from Start Hole Reviewed

    Akiyoshi Kawata, Akira Okada, Yasuhiro Okamoto, Haruya Kurihara

    Key Engineering Materials (Recent Development in Machining, Materials and Mechanical Technologies II)   ( 749 )   130 - 135   2017.8

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  • Multi-wire EDM slicing of semiconductors with group power supplying method Reviewed

    Yasuhiro Okamoto, Takayuki Ikeda, Haruya Kurihara, Akira Okada, Masataka Kido

    Proceedings of euspen's 17th International Conference   183 - 184   2017.5

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  • Fabrication of Multi-layered Artificial Skin Using Individual Digital Shade Guide Reviewed

    Qiuyue Pan, Naoto Maeda, Yasuhiro Okamoto, Keiji Jind, Goro Nishigawa and Shogo Minagi

    The Journal of Okayama Dental Society   35 ( 2 )   53 - 57   2017.3

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  • Study on Reduction of Discoloration Area in Micro-drilling of Multi-layered Artificial Skin by Picosecond Pulsed Laser Reviewed

    Yasuhiro Okamoto, Akira Eguchi, Naoto Maeda, Akira Okada, Shogo Minagi, Qiuyue Pan, Keiji Jin, Goro Nishigawa

    International Journal of Electrical Machining   ( 22 )   8 - 13   2017.3

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  • Effects of Pulse Duration on Removal Characteristics of Silver Nanowire Transparent Conductive Film by Nanosecond Pulsed Laser Reviewed

    Norio Nishi, Yasuhiro Okamoto, Masafumi Oshita, Akira Okada, Togo Shinonaga, Tomokazu Sakagawa

    Journal of Materials Processing Technology   240   255 - 261   2017.2

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  • Multi-wire EDM slicing of Semiconductors with Group Power Supplying Method Reviewed

    Yasuhiro Okamoto, Takayuki Ikeda, Haruya Kurihara, Akira Okada, Masataka Kido

    Proceedings of euspen's 17th International Conference   183 - 184   2017

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  • Fabrication of Multi-layered Artificial Skin Using Individual Digital Shade Guide Reviewed

    Qiuyue Pan, Naoto Maeda, Yasuhiro Okamoto, Keiji Jind, Goro Nishigawa, Shogo Minagi

    The Journal of Okayama Dental Society   35 ( 2 )   53 - 57   2017

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  • Study on Reduction of Discoloration Area in Micro-drilling of Multi-layered Artificial Skin by Picosecond Pulsed Laser Reviewed

    Okamoto Yasuhiro, Eguchi Akira, Maeda Naoto, Okada Akira, Minagi Shogo, Pan Qiuyue, Jin Keiji, Nishigawa Goro

    International Journal of Electrical Machining   22 ( 22 )   8 - 13   2017

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    <p> A multi-layered artificial skin, which is mainly consisted of three layers of silicone elastomer, printed paper, and resin plate, is expected as sealing material of facial defects. However, sweating phenomenon from the surface of missing parts results in insanitary conditions to the skin surface, and micro-drilled holes are required to improve the breathability of the multi-layered artificial skin as human's sweat glands. High-efficiency processing is expected by using a high pulse repetition-rate laser. Although ultra-short pulsed laser is used, a continuous long time laser irradiation deteriorated the aesthetic quality of multi-layered artificial skin because of heat accumulation corresponding to the high pulse-repetition-rate. Therefore, laser irradiation method with the high-efficiency and good-aesthetic-quality was experimentally investigated by using picosecond pulsed laser of 1064 nm wavelength. The laser irradiation method, which can reduce the heat affected zone at the adhesion part between the print paper and the silicone elastomer, was effective in order to improve the esthetic quality of drilled hole for the multi-layered artificial skin. The discoloration area around drilled hole on multilayered artificial skin could be reduced by dividing method of laser shot number at the same irradiation point to provide non-irradiation time. A long non-irradiation time resulted in the reduction of discoloration area around drilled hole on multi-layered artificial skin under the similar heat input condition.</p>

    DOI: 10.2526/ijem.22.8

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  • Influence of nozzle jet flushing on wire breakage in 1st-cut wire edm from start hole Reviewed

    Akiyoshi Kawata, Akira Okada, Yasuhiro Okamoto, Haruya Kurihara

    Key Engineering Materials   749   130 - 135   2017

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    In wire EDM (electrical discharge machining) process, it is important to smoothly exclude debris and bubbles generated in the working gap for keeping stable performance. Much debris stagnation in the gap would cause frequent occurrence of discharge concentration and secondary discharge, which results in unstable machining performance, such as frequent wire breakage, low removal rate, and low shape accuracy. Therefore, a jet flushing of working fluid using upper and lower jet nozzles has been conventionally applied for excluding the debris and bubbles from the machined kerf. Nevertheless, it is well known that the wire often breaks when the machined kerf length is a few mm from the start hole in 1st-cut wire EDM. The influence of machined kerf length on the flow field, the debris exclusion, and the wire behavior caused with hydrodynamic force by the jet flushing should be made clear. In this study, variations of flow field in the kerf, the debris accumulation state and the wire deflection caused jet flushing with machined length were analytically investigated by CFD (computational fluid dynamics) and structural analysis when 1st-cut wire EDM was done from a small start hole. Moreover, the effects of machined kerf length on the wire deflection and wire breakage were discussed. Wire breakage frequency experiments showed that wire tended to frequently break at a certain machined kerf length, where the wire deflection rapidly increased and the debris residence time in the gap became long.

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  • Effect of focusing condition on molten area characteristics in micro-welding of borosilicate glass by picosecond pulsed laser Reviewed

    I. H. W. Nordin, Y. Okamoto, A. Okada, T. Takekuni, T. Sakagawa

    APPLIED PHYSICS A-MATERIALS SCIENCE & PROCESSING   122 ( 5 )   2016.5

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    The characteristics of the molten area are attributed not only by laser energy condition but also the focusing condition. In this study, a picosecond pulsed laser of 1064 nm in wavelength and 12.5 ps in pulse duration was used as a laser source for joining glass material. Influence of focusing condition on micro-welding of glasses was experimentally investigated by using an objective lens with and without spherical aberration correction, and its molten area was characterized. The usage of objective lens with spherical aberration correction led to a larger molten area inside the bulk material of glass even under the same pulse energy, which related to the efficient micro-welding of glass materials. In addition, an optical system with the spherical aberration correction led to a stable absorption of laser energy inside the bulk glass material, stabilizing the shape of molten area, which resulted in the reliable weld joint. On the other hand, breaking strength of the specimens with spherical aberration correction was higher than that without spherical aberration correction. Therefore, it is concluded that the focusing condition with spherical aberration correction led to the larger and stable molten area, which resulted in higher joining strength in micro-welding of glass materials.

    DOI: 10.1007/s00339-016-0026-7

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  • Thermo-Mechanical Analysis on Thermal Deformation of Thin Stainless Steel in Laser Micro-Welding Reviewed

    Mohd Idris Shah Ismail, Yasuhiro Okamoto, Akira Okada

    International Journal of Manufacturing, Materials, and Mechanical Engineering   6 ( 2 )   51 - 66   2016.4

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    In the present study, a three-dimensional finite element model has been developed to simulate the temperature, stress and deformation fields in continuous wave (CW) laser micro-welding of thin stainless steel sheet. The welding deformation was experimentally evaluated using a single-mode fiber laser with a high-speed scanning system. Application of developed thermal model demonstrated that the laser parameters, such as laser power, scanning velocity and spot diameter have a significant effect on temperature field and the weld pool. In the case of welding deformation, numerical simulation was carried out by an uncoupled thermo-mechanical model. The welding stress and deformation are generated by plastic deformation during the heating and cooling periods. It was confirmed that the residual stress is higher than yield strength and has strongest effect upon the welding deformation. The numerical simulated results have proved that the developed finite element model is effective to predict thermal histories, thermally induced stresses and welding deformations in the thin material.

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  • Effect of wavelength and pulse duration on laser micro-welding of monocrystalline silicon and glass Reviewed

    I. H. W. Nordin, Y. Okamoto, A. Okada, H. Jiang, T. Sakagawa

    APPLIED PHYSICS A-MATERIALS SCIENCE & PROCESSING   122 ( 4 )   1 - 7   2016.4

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    Micro-welding characteristics of silicon and glass by pulsed lasers are described. In this study, four types of laser beam, which are nanosecond pulsed laser and picosecond pulsed laser of 532 and 1064 nm in wavelength, were used for joining monocrystalline silicon and glass. Influence of wavelength and pulse duration on micro-welding of monocrystalline silicon and glass was experimentally investigated under the same spot diameter, and the molten area of monocrystalline silicon and glass was characterized. Finally, the breaking strength was evaluated for the overlap weld joint with different pulse duration and wavelength. A splash area of molten silicon around the weld bead line was obvious in the nanosecond pulsed laser. On the other hand, there was no remarkable molten splash around the weld bead line in the picosecond pulsed laser. Breaking strength of specimens with 1064 nm wavelength was higher than with 532 nm wavelength in nanosecond laser, whereas breaking strength of laser-irradiated specimen by picosecond pulse duration was higher than that by nanosecond pulse duration. It is concluded that the combination of picosecond pulse duration and infrared wavelength leads to the stable molten area appearance of the weld bead and higher breaking strength in microwelding of glass and monocrystalline silicon.

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  • Effects of Surface States on Light Absorption Characteristics in Laser Micro-welding of Copper

    Inoue Reiki, Wada Takuya, Okamoto Yasuhiro, Okada Akira, Nakashiba Shinichi, Sakagawa Tomokazu

    Proceedings of JSPE Semestrial Meeting   2016   835 - 836   2016

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    DOI: 10.11522/pscjspe.2016S.0_835

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  • Influence of Pulse duration on Processing Characteristics of Transparent Conductive Film Containing Silver Nanowires by ns Pulsed Fiber Laser Reviewed

    Masafumi Oshita, Norio Nishi, Yasuhiro Okamoto, Akira Okada, Togo Shinonaga, Tomokazu Sakagawa

    18TH CIRP CONFERENCE ON ELECTRO PHYSICAL AND CHEMICAL MACHINING (ISEM XVIII)   42   62 - 66   2016

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    Processing characteristics of transparent conductive film containing silver nanowires by ns pulsed fiber lasers with various pulse duration were experimentally investigated in the view-points of insulating state and surface quality. The laser fluence achieving the insulation state became smaller with decreasing the pulse duration. Appearance of removed trace area of silver nanowires was varied by the pulse duration, and the removal area ratio of removed trace area to the whole one was evaluated to discuss the surface quality. Small removal area ratio and good insulation state could be performed at a wide processing window at long pulse duration of 200ns. (C) 2016 The Authors. Published by Elsevier B.V.

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  • Investigation of Shielding Gas Supplying Method in Vertical-position Laser Welding of Pure Titanium Reviewed

    Kazuo Yokohara, Yasuhiro Okamoto, Akira Okada, Hikotaro Ochiai, Ryosuke Kimura, Shozo Ono, Masayuki Akase

    18TH CIRP CONFERENCE ON ELECTRO PHYSICAL AND CHEMICAL MACHINING (ISEM XVIII)   42   448 - 453   2016

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    Effective shielding method for a wide area is required in the vertical-position remote laser welding of pure titanium. Therefore, shielding effects of ring-type nozzles with two layers for a wide area were numerically and experimentally investigated in the vertical-position setup of workpiece with argon gas. Prevention of incoming air flow outside a ring-type nozzle is effective to increase mass fraction of argon gas. Mass fraction of argon gas could be increased using a ring-type nozzle, in which shielding gas is supplied by open-side injection ports of proper angle at a proper flow ratio of two jetting layers. (C) 2016 The Authors. Published by Elsevier B.V.

    DOI: 10.1016/j.procir.2016.02.230

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  • Improvement in Surface Characteristics by EDM with Chromium Powder Mixed Fluid Reviewed

    Ryota Toshimitsu, Akira Okada, Ryoji Kitada, Yasuhiro Okamoto

    18TH CIRP CONFERENCE ON ELECTRO PHYSICAL AND CHEMICAL MACHINING (ISEM XVIII)   42   231 - 235   2016

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    Surface finishing technology by EDM has recently progressed, and very small surface roughness can be readily obtained by controlling the electrical discharge conditions, or by using metal powder mixed working fluids. In addition, it was reported that EDMed surface using metal powder mixed fluids sometimes has high surface functions, such as high hardness, high corrosion resistance and so on. Therefore, the high functional EDM finished surface is well expected to be applied as a final metal mold surface. In this study, formation of chromium containing layer on the EDMed surface was tried by using chromium powder mixed fluid. Furthermore, the EDMed surface characteristics with chromium powder mixed fluid were experimentally evaluated. (C) 2016 The Authors. Published by Elsevier B.V.

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  • High-speed Observation of Thin Wire Movement in Fine Wire EDM Reviewed

    Takuya Kamei, Akira Okada, Yasuhiro Okamoto

    18TH CIRP CONFERENCE ON ELECTRO PHYSICAL AND CHEMICAL MACHINING (ISEM XVIII)   42   596 - 600   2016

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    In this study, the movements of thin tungsten wire electrode during fine wire EDM were investigated by direct observation using a high-speed camera. The results showed that the amplitude in the direction parallel to the machining direction was a little larger than that in the perpendicular one. Also, the backward wire deflection could be confirmed even in fine wire EDM. Furthermore, the wire vibration mode was found out by frequency analysis and the vibration amplitude could be reduced by adjusting the workpiece position to the 3rd order node of the vibration. In addition, the amplitude envelope of wire electrode during the process was clarified. (C) 2016 The Authors. Published by Elsevier B.V.

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  • Formation of periodic nanostructures with femtosecond laser for creation of new functional biomaterials Reviewed

    Togo Shinonaga, Shono Kinoshita, Yasuhiro Okamoto, Masahiro Tsukamoto, Akira Okada

    18TH CIRP CONFERENCE ON ELECTRO PHYSICAL AND CHEMICAL MACHINING (ISEM XVIII)   42   57 - 61   2016

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    Pure Titanium (Ti) and Ti alloys are the most used biomaterials. However, they have problem for bioactivity because metals have no biofunction. Therefore, adding new function to Ti and Ti alloys are necessary. One method to add new function is the creation of periodic structures on the biomaterial surfaces, which can control cell spreading. Femtosecond laser is one of the useful tools for creating periodic nanostructures, which can be created on metals and semiconductors by self-organizing in the laser focusing spot. In our previous study, the nanostructures could be formed on the Ti plate by using the femtosecond laser with fundamental wavelength of 775 nm. The periodicities of the nanostructures on the Ti plate was approximately 590 nm, which was shorter than the laser wavelength. Cells tests indicated that cell spreading clearly occurs along the grooves of the nanostructures. However, the influence of the periods of the nanostructure on cell spreading has not yet been investigated. It is expected that the periods can be varied by changing laser parameters, such as pulse widths, laser wavelengths, laser fluences, and number of shots. In this study, the periodic nanostructures are created on the Ti plate surface by using the femtosecond laser with fundamental wavelength of 790 nm. Then, influence of the pulse width and number of shots on the periods is investigated. In the experiments, laser beam is focused and scanned on the Ti plate surfaces. The laser irradiated areas are analysed by using a scanning electron microscope (SEM).

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  • Evaluation of molten area in micro-welding of monocrystalline silicon and glass Reviewed

    I. H. W. Nordin, Y. Okamoto, I. Miyamoto, A. Okada

    2ND INTERNATIONAL MANUFACTURING ENGINEERING CONFERENCE AND 3RD ASIA-PACIFIC CONFERENCE ON MANUFACTURING SYSTEMS (IMEC-APCOMS 2015)   114   2016

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    Characteristics of the molten area in micro-welding of monocrystalline silicon and glass are described. In this study, 4 types of laser beam, which are nanosecond pulsed laser and picosecond pulsed laser of 532 nm and 1064 nm in wavelength were used for joining monocrystalline silicon and glass. Influence of wavelength and pulse duration on micro-welding of monocrystalline silicon and glass was experimentally investigated under the same spot diameter, and the molten area of monocrystalline silicon and glass was characterized. A splash area of molten silicon with 532 nm wavelength was wider than that with 1064 nm in a nanosecond pulse laser. However, its splash area of molten silicon with 1064 nm changed drastically at certain pulse energy of 11 mu J in a nanosecond pulse laser. On the other hand, 12.5 ps pulsed laser still kept a stable molten area appearance even at pulse energy of 11 mu J. A splash area of molten silicon around the weld bead line was obvious in the nanosecond pulsed laser. On the other hand, there was no remarkable molten splash around the weld bead line in the picosecond pulsed laser. It is concluded that the combination of picosecond pulse duration and infrared wavelength leads to a stable molten area appearance of the weld bead.

    DOI: 10.1088/1757-899X/114/1/012039

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  • Investigation on Visibility of Drilled Hole in Laser Micro-drilling of Multi-layered Artificial Skin Reviewed

    Okamoto Yasuhiro, Asako Kiichi, Maeda Naoto, Okada Akira, Minagi Shogo, Pan Qiuyue, Jin Keiji, Nishigawa Goro

    International Journal of Electrical Machining   21 ( 21 )   13 - 17   2016

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    A multi-layered artificial skin is mainly consisted of three layers of silicone elastomer, print paper, and resin plate. Sealing of facial defects with the multi-layered artificial skin causes perspired water from the surface of missing parts, which results in insanitary conditions to the skin surface. Therefore, the laser micro-drilling using nanosecond pulsed laser of 266 nm was investigated to provide the breathability for multi-layered artificial skin without human eye's recognition of drilled holes, which can satisfy both the breathability and aesthetic problems. The visibility of drilled hole was affected by the pitch distance of drilled holes, and its visibility decreased with increasing the pitch distance. A small color difference measured using a colorimeter led to the low visibility, and laser micro-drilling with small color difference is effective to obtain the breathable multi-layered artificial skin with low visibility of drilled holes, which can improve the breathability for the multi-layered artificial skin.

    DOI: 10.2526/ijem.21.13

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  • 1203 High-quality and Reliable Removal Method of ZnO by ns Pulsed Fiber Laser with Square Core Optical Fiber Reviewed

    NISHI Norio, OKAMOTO Yasuhiro, OKADA Akira, NAKASHIBA Shin-ichi, SAKAGAWA Tomokazu

    Proceedings of International Conference on Leading Edge Manufacturing in 21st century : LEM21   2015 ( 8 )   "1203 - 1"-"1203-6"   2015.10

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    Effects of edge intensity distribution in top-hat mode on removal characteristics of zinc oxide film was experimentally investigated by a nano-second pulsed fiber laser. The usage of mask could change the edge intensity distribution of laser beam. The combination of singlet lens and slit mask could perform the gradual edge and the sharp edge intensity distributions in parallel and perpendicular directions to a scanning line, respectively. This edge intensity combination could achieve high-quality removal with narrow damaged regions around the scribed grooves and reliable removal with stable electrical insulation states at more than a proper overlap rate.

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  • Effect of surrounding gas condition on surface integrity in micro-drilling of SiC by ns pulsed laser Reviewed

    Yasuhiro Okamoto, Kiichi Asako, Norio Nishi, Tomokazu Sakagawa, Akira Okada

    APPLIED PHYSICS B-LASERS AND OPTICS   119 ( 3 )   509 - 517   2015.6

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    The influence of the surrounding gas conditions on the surface integrity in the micro-drilling of silicon carbide was experimentally investigated using ns pulsed laser of 266 nm wavelength. Moreover, micro-machining characteristics were observed using high-speed shutter and video cameras in the micro-drilling of silicon carbide. The size and intensity of the laser-induced plasma were larger, and the plasma affected area was larger and deeper in argon than that in air. Although the intensity of the plasma was lower in helium than that in other gases, the surface around the drilled hole was roughened by the spread of the plasma in the vicinity of the drilled hole. Debris was removed along the flow field generated by laser shot in the opposite direction to the laser irradiation. The gas flow behavior and the spectrum and intensity of the laser-induced plasma were influenced by the surrounding gas type and pressure. The appearance of plasma generation affected the surface integrity at the circumference of the drilled hole, and the surface integrity was improved by reducing the pressure.

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  • High speed, high strength microwelding of Si/glass using ps-laser pulses Reviewed

    Isamu Miyamoto, Yasuhiro Okamoto, Assi Hansen, Joma Vihinen, Tiina Amberla, Jarno Kangastupa

    OPTICS EXPRESS   23 ( 3 )   3427 - 3439   2015.2

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    A novel microwelding procedure to join Si-to-glass using ps-laser pulses with high repetition rates is presented. The procedure provides weld joint with mechanical strength as high as 85 MPa and 45 MPa in sample pairs of Si/aluminosilicate (Si/SW-Y) and Si/borosilicate (Si/Borofloat 33), respectively, which are higher than anodic bonding, at high spatial resolution (&lt; 20 mu m) and very high throughput without pre- and post-heating. Laser-matter interaction analysis indicates that excellent weld joint of Si/glass is obtained by avoiding violent evaporation of Si substrate using ps-laser pulses. Laser welded Si/glass samples can be singulated along the weld lines by standard blade dicer without defects, demonstrating welding by ps-laser pulses is applicable to wafer-level packaging. (C)2015 Optical Society of America

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  • Investigation of Laser Micro-drilling Method for Multi-Layered Artificial Skin

    Asako Kiichi, Okamoto Yasuhiro, Okada Akira, Minagi Shogo, Maeda Naoto, Pan Qiuyue, Jin Keiji, Nishikawa Goro

    Proceedings of JSPE Semestrial Meeting   2015   691 - 692   2015

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    DOI: 10.11522/pscjspe.2015S.0_691

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  • Investigation of Processing Characteristics of Transparent Conductive Film Containing Silver Nanowires by ns Pulsed Fiber Laser

    Oshita Masafumi, Nishi Norio, Yokoyama Takehito, Okamoto Yasuhiro, Okada Akira

    Proceedings of JSPE Semestrial Meeting   2015   689 - 690   2015

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  • Effect of Focusing Condition on ps Pulsed Laser Welding of Glass

    Ota Motoki, Okamoto Yasuhiro, Shinonaga Togo, Okada Akira

    Proceedings of JSPE Semestrial Meeting   2015   181 - 182   2015

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  • Study on periodic nanostructures formation by ultrashort pulse laser irradiation for adding function of controlling cell spreading

    Shinonaga Togo, Kinoshita Shono, Okamoto Yasuhiro, Tsukamoto Masahiro, Okada Akira

    Proceedings of JSPE Semestrial Meeting   2015   185 - 186   2015

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    DOI: 10.11522/pscjspe.2015A.0_185

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  • Film Formation Mechanism in Alumina Coating by Large-area Electron Beam Irradiation

    Takata Masashi, Okada Akira, Okamoto Yasuhiro, Inoue Motohiro, Sano Sadao

    Proceedings of JSPE Semestrial Meeting   2015   1077 - 1078   2015

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    In our previous studies, the possibility of thin ceramic film formation by using a large-area EB irradiation was shown. However, the film formation mechanism has not yet been clarified. In this report, the influences of magnetic and electrical conductivity of a jig supporting an alumina target tube on the film formation were investigated, and the spectrum of plasma generated on the substrate surface during the EB irradiation was measured in order to clarify the mechanism. As a result, it was made clear that the film was formed by sputtering target material with the plasma of workpiece material caused by EB Irradiation.

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  • Smart laser micro-welding of difficult-to-weld materials for electronic industry Reviewed

    Y. Okamoto, N. Nishi, S. Nakashiba, T. Sakagawa, A. Okada

    LASER-BASED MICRO- AND NANOPROCESSING IX   9351   2015

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    It has been known that wavelength, power density, interaction time and material properties have great influence on processing characteristics in laser material processing, in which materials with higher reflectivity classify into difficult-to-weld materials. In electronic industry, aluminum alloy is widely used as structural components due to its high specific strength, and copper became an important material because of its excellent electrical conductivity. These materials have high reflectivity and high thermal conductivity, which results in instability of energy absorption and processing results. Therefore, welding defects might be noticed in the micro-joining of aluminum alloy and copper. In this paper, the smart laser micro-welding of difficult-to-weld materials such as aluminum alloy and copper were discussed. The combination of a pulsed Nd:YAG laser and a continuous diode laser could perform high-performance micro-welding of aluminum alloy. A pulsed Nd:YAG laser was absorbed effectively from the beginning of laser scanning by pre-heating Nd:YAG laser pulse with the superposition of continuous diode laser, and wide and deep weld bead could be obtained with better surface integrity. As for micro-welding of copper material, stable absorption state could be achieved using a pulsed green Nd:YAG laser, since its absorptivity showed almost constant values with change of power density. A longer pulse duration was effective to achieve not only high absorptivity but also low deviation of absorptivity. The pulse waveform with maximum peak at the early period and a long pulse duration led to stabilizing the penetration depth with less porosity.

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  • Study on surface characteristics of EDMed surface with nickel powder mixed fluid

    Shuhei Iwasaki, Ryoji Kitada, Akira Okada, Yasuhiro Okamoto

    Key Engineering Materials   656-657   375 - 380   2015

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    EDM finishing techn ology has progressed recently, and very small surface roughness can be obtained by controlling the electrical discharge conditions. Also, EDM using powder mixed fluids can improve the surface characteristics. Therefore, the EDM finished surface is highly expected to be applied as a final metal mold surface. In that case, the characteristics of EDMed surface affects the molding performance and the life of metal molds. As a new surface finishing method by EDM, the characteristics of EDMed surface using a nickel powder mixed fluid was experimentally discussed in this study, since nickel coatings have been widely applied to improve the corrosion resistance and the mold releasability of metal molds. Experimental analysis clarified that the resolidified layer containing nickel content could be formed on the surface by EDM in nickel powder mixed fluid. Also, the water repellency and the releasability of molded resin from the EDM finished surface could be improved.

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  • Study on applicability of large-area EB irradiation to micro-deburring

    Tomoaki Miyoshi, Akira Okada, Yasuhiro Okamoto

    Key Engineering Materials   656-657   369 - 374   2015

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    In a large-area electron beam (EB) irradiation method developed recently, high energy EB can be obtained without focusing the beam, and large-area EB with almost uniform energy density distribution of 60mm in diameter can be used for instantly melting and evaporating metal surface. Then, the surface smoothing and surface modification of metal molds made of steel, cemented carbide and ceramics can be performed efficiently. When the large-area EB is irradiated to a sharp edge, the material removal remarkably progresses at the edge due to the heat accumulation and EB concentration there, which leads to the edge rounding. Our previous study clarified that micro-deburring was also possible by using this phenomenon. Moreover, this method would be effective for removal of discontinuous micro burrs generated by thermal machining processes, such as EDM and laser cutting. In this study, the possibility to completely remove micro burrs generated in EDM was experimentally investigated. The difference in micro-deburring characteristics with the type of workpiece material was also investigated. As a result, the EDM micro burrs with a height of about up to 50μm could be completely removed by this method. Furthermore, it was made clear that the magnetic property of workpiece materials greatly influenced the deburring characteristics, and the thermal property such as melting point and thermal conductivity also did.

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  • Effect of Tilting Jet Flushing Nozzle on Wire EDM Performance Reviewed

    Konishi Takuro, Okada Akira, Okamoto Yasuhiro, Kurihara Haruki

    International Journal of Electrical Machining   20 ( 20 )   2 - 8   2015

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    Debris exclusion from the wire EDM gap has been conventionally done by jet flushing using nozzles but the debris stagnation area always presents near the wire with the conventional method. In this study, a new flushing method using tilting nozzle to wire running direction to reduce the debris stagnation in the kerf was proposed on the base of simulation results by computational fluid dynamics (CFD) analysis. The simulations and experiments clarified that the tilting jet flushing nozzle could decrease the debris stagnation area in the kerf and leads to smoother debris exclusion, resulting in higher removal rate. Furthermore, the wire deflection caused by hydrodynamic force due to the jet flushing was calculated by a structural analysis using the distributions of pressure acting on the wire surface by jet flushing flow obtained by the CFD analysis.

    DOI: 10.2526/ijem.20.3

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  • Influence of Bead Geometry on Weld Distortion in Laser Micro-welding of Thin Stainless Steel Sheet with High-speed Scanning Reviewed

    Okamoto Yasuhiro, Matsuoka Satoshi, Otowa Tadanori, Okada Akira

    International Journal of Electrical Machining   20 ( 20 )   9 - 15   2015

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    In this study, the thermal deformation of thin stainless steel sheet was investigated in bead-on-plate welding by using a single-mode fiber laser with Galvano scanning system. The numerical simulation was carried out to calculate temperature and stress fields, and its deformation characteristics were discussed. It was suggested that a specimen firstly deformed downward in the same direction of laser irradiation, and then deformed in the reversed direction after laser scanning. The final distortion angle in the negative direction, which is concave shape from the view direction of laser irradiation, was generated under the heat conduction and quasi-penetration welding mode, and the positive angle was obtained as the final distortion angle under the full-penetration welding mode. On the other hand, a small distortion could be achieved by the proper weld bead geometry in micro-welding of thin sheet, but the welding mode of minimum distortion conditions varied with specimen thickness. However, these relationships obtaining a small distortion could be understood by the relationship between aspect ratio of weld bead and distortion angle. Minimum angle of distortion could be achieved around maximum aspect ratio of weld bead regardless of specimen thickness and spot diameter, when an inflection point appeared in relationship between aspect ratio of weld bead geometry and distortion angle.

    DOI: 10.2526/ijem.20.9

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  • Effect of Laser Beam Intensity Distribution in Removal Processing of ZnO Film by ns Pulsed Fiber Laser of Square Core Reviewed

    Norio NISHI, Yasuhiro OKAMOTO, Takehito YOKOYAMA, Akira OKADA, Shin-ichi NAKASHIBA, Tomokazu SAKAGAWA

    Journal of the Japan Society for Precision Engineering   81 ( 11 )   1033 - 1038   2015

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    Removal characteristics of zinc oxide film used as a transparent conductive oxide were experimentally investigated using a square fiber and nano-second pulsed laser. Effects of the intensity distribution of the laser beam on removal phenomena were discussed with a combination of an achromatic lens and a single lens. An achromatic lens achieved better groove shapes with a narrow damaged region, but the electrical insulation state was unstable, in which scribed groove could not achieve insulation state even at a higher overlap rate around 80%. High-speed observation revealed a possibility of zinc oxide film remaining on the glass substrate, since dominant removal of zinc oxide film progressed uniformly inside the spot area in thickness direction of film. On the other hand, a single lens resulted in a wide damaged region, but the electric insulation was obtained stably at more than a certain overlap rate. Because zinc oxide film was removed from center to outer side inside the laser spot with pushing material in width direction, and zinc oxide film was almost completely removed at the center area of laser spot. Therefore, the combination of a singlet lens and a slit mask was proposed to attempt different intensity distribution in parallel and perpendicular direction to scanning line. This optical setup could achieve both stable electric insulation state and better groove shapes with a narrow damaged region at more than overlap rate of 60%.

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  • Wire breakage and deflection caused by nozzle jet flushing in wire EDM Reviewed

    A. Okada, T. Konishi, Y. Okamoto, H. Kurihara

    CIRP ANNALS-MANUFACTURING TECHNOLOGY   64 ( 1 )   233 - 236   2015

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    High flow rate in nozzle jet flushing is effective for smooth debris exclusion from the wire EDM gap, but this leads to large wire deflection and vibration, resulting in the wire breakage and low shape accuracy. In this paper, the influence of nozzle jet flushing on wire breakage was experimentally investigated with varying the machined kerf length and machining conditions. Furthermore, the flow fields and debris residence time in the kerf, hydrodynamic stress distributions acting on the wire, and wire deflections were numerically analyzed. Based on the analyzed results, the causes of wire breakage were discussed. (C) 2015 CIRP.

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  • Effects of focusing condition on micro-welding characteristics of borosilicate glass by picosecond pulsed laser

    Tomohiro Takekuni, Yasuhiro Okamoto, Takahiro Fujiwara, Akira Okada, Isamu Miyamoto

    Key Engineering Materials   656-657   461 - 467   2015

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    Glass materials are widely used in products such as optical components and semiconductor devices. In these products, precision welding techniques of glass are required to manufacture small and complicated shape. The laser welding method can perform the joining without an intermediate layer and an adhesive agent. In addition, an ultra-short pulse laser can reduce the heat affected zone with the high space accuracy. However, heating and cooling cycles are repeated even in the case of ultra-short pulsed laser. The temperature distribution and change of molten area are influenced not only by laser energy condition but also focusing condition. Therefore in this study, effects of focusing condition of laser beam on micro-welding characteristics of glass were experimentally investigated by using a picosecond pulsed laser. A usage of object lens with the spherical aberration correction led to a large molten area even at the same pulse energy, which related to the efficient welding of glass materials. An optical system with the spherical aberration correction led to stabilizing the shape of molten area, which resulted in the reliable weld joint.

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  • Improvement of surface characteristics for long life of metal molds by large-area EB irradiation Reviewed

    Akira Okada, Yasuhiro Okamoto, Yoshiyuki Uno, Kensuke Uemura

    JOURNAL OF MATERIALS PROCESSING TECHNOLOGY   214 ( 8 )   1740 - 1748   2014.8

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    This paper describes the applicability of large-area EB irradiation method to a new surface modification for metal molds. The previous papers clarified that the surface roughness on wide area uniformly decreased to less than 1 mu m Rz in a few minutes by the large-area EB irradiation. Therefore, the large-area EB irradiation method has high practicability as an efficient surface finishing process for metal molds, and then the EB irradiation equipment has already been introduced into the market for practical use. In this method called EB polishing, the surface material melts and a very thin resolidified layer is formed on the surface. In this paper, the surface structure of EB polished metal mold steel SKD11 was first observed by TEM, and also component analysis was carried out by EDX. Then it was found out that the crystal grain size became small and chromium carbide is uniformly rearranged in the layer. Next, using heat conduction analysis model considering the electron penetration on the surface, the temperature distribution was calculated. The results showed that the surface temperature rapidly raised over its melting point until the end of EB irradiation, and cooled down rapidly. As the important practical surface characteristics for long life of metal mold, resistance to corrosion, water repellency, and the releasability of molded resin from metal mold surface were evaluated. The corrosion resistance and the water repellency could be improved by EB polishing, since the surface structure changes and Cr content distributed uniformly on the surface. Also, the releasability of molded resin from the surface became better. (C) 2014 Elsevier B.V. All rights reserved.

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  • Fundamental study on releasability of molded rubber from mold tool surface

    Akira Okada, Yasuhiro Okamoto, Adam Clare, Yoshiyuki Uno

    INTERNATIONAL JOURNAL OF ADVANCED MANUFACTURING TECHNOLOGY   70 ( 5-8 )   1515 - 1521   2014.2

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    In compression or injection molding of rubber products, small pieces of residual rubber often remain on the metal mold surface after releasing the product. This is caused by excessive localized adhesion to the mold surface. Therefore, cleaning of metal mold surface must be often performed, which results in longer molding cycle time, and the lifetime of metal mold is often reduced. In this study, the separation forces between molded rubber and metal mold surfaces are measured with a tensile tester to evaluate the releasability of molded rubber from the metal mold surface. Mold surfaces treated by various surface coatings and surface modification methods including EB polishing were tested and compared. Experimental results show that the separation force between molded rubber and metal mold surfaces depends on the true contact area between them and the chemical composition of the metal mold surface. The separation force decreases with a decrease in contact area. The chromium content at the metal mold surface significantly reduces the separation force. EB polishing is one of the most effective surface treatments for metal molds since the real contact area can be decreased while also decreasing the surface roughness of the tool surface in a short time. Electron beam melting is also shown to be an effective method of distributing chromium uniformly on the metal mold surface.

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  • Internal modification of glass by ultrashort laser pulse and its application to microwelding Reviewed

    Isamu Miyamoto, Kristian Cvecek, Yasuhiro Okamoto, Michael Schmidt

    APPLIED PHYSICS A-MATERIALS SCIENCE & PROCESSING   114 ( 1 )   187 - 208   2014.1

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    Internal modification process of glass by ultrashort laser pulse (USLP) and its applications to microwelding of glass are presented. A simulation model is developed, which can determine intensity distribution of absorbed laser energy, nonlinear absorptivity and temperature distribution at different pulse repetition rates and pulse energies in internal modification of bulk glass with fs- and ps-laser pulses from experimental modified structure. The formation process of the dual-structured internal modification is clarified, which consists of a teardrop-shaped inner structure and an elliptical outer structure, corresponding to the laser-absorbing region and heat-affected molten region, respectively. Nonlinear absorptivity at high pulse repetition rates increases due to the increase in the thermally excited free electron density for avalanche ionization. USLP enables crack-free welding of glass because the shrinkage stress is suppressed by producing embedded molten pool by nonlinear absorption process, in contrast to conventional continuous wave laser welding where cracks cannot be avoided due to shrinkage stress produced in cooling process. Microwelding techniques of glass by USLP have been developed to join glass/glass and Si/glass using optically contacted sample pairs. The strength of the weld joint as high as that of base material is obtained without pre- and post-heating in glass/glass welding. In Si/glass welding, excellent joint performances competitive with anodic bonding in terms of joint strength and process throughput have been attained.

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  • Study on Possibility of Micro-deburring by Large-area Electron Beam Irradiation Reviewed

    Yonehara Hajime, Okada Akira, Okamoto Yasuhiro

    IJEM   19 ( 19 )   22 - 27   2014

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    In a large-area electron beam (EB) irradiation method developed recently, high energy EB can be obtained without focusing the beam. Therefore, the large-area EB of 60mm in diameter with almost uniform energy distribution can be used for instant melting and evaporating of metal surface. The previous studies clarified that the surface smoothing of metal mold made of steel, cemented carbide and ceramics could be performed efficiently. Also this method can be applied to the surface finishing of biomaterials, such as stainless steel and titanium alloy. In this method, the sharp edge is possibly rounded to about half hundred microns in radius under relatively high energy density conditions, since the material removal remarkably progresses there due to the electron concentration and heat accumulation at the edge. In this study, the possibility of micro-deburring was investigated by using the preferential edge removal effect in the large-area EB irradiation. Experimental results showed that the micro-deburring was possible by large-area EB irradiation, and the burr height decreased with increasing energy density of EB and number of irradiation. The burr of about 50μm in height generated in EDM process could be removed completely. Furthermore, micro-burrs at the edge of several small holes within the wide area of 60mm in diameter could be removed simultaneously.

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  • Singulation Characteristics of Semiconductor Package Using Pulsed Fiber Laser and SHG:YAG Laser Reviewed

    Okamoto Yasuhiro, Kitada Ryoji, Okada Akira, Uno Yoshiyuki

    IJEM   19 ( 19 )   28 - 33   2014

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    A laser singulation method by the superposition of a pulsed fiber laser and an SHG:YAG laser (SHG: Second Harmonic Generation) was proposed to perform the high-quality processing of semiconductor packages, which are consisted of thermosetting epoxy-resin with silica as the molding compounds and a glass epoxy board with insulator coatings for the semiconductor package. The superposition of the pulsed fiber laser and SHG:YAG laser with a high pulse repetition rate led to a straighter kerf shape with a smaller kerf width under the same pulse energy condition. A smaller kerf width was achieved by controlling the time-delay between the laser pulses compared with synchronized laser pulses. The heat affected zone from the cut surface was reduced by the superposition of the pulsed fiber laser and SHG:YAG laser. Moreover, synchronized laser pulses led to a smaller heat affected zone compared with unsynchronized pulses.

    DOI: 10.2526/ijem.19.28

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  • The Boundary of Key-hole Generation in Micro-welding of Aluminum Alloy by Pulsed Nd:YAG Laser with Superposition of Continuous Diode Laser Reviewed

    中芝伸一, 岡本康寛, 酒川友一, 原田昌宜, 岡田晃

    精密工学会誌(Web)   80 ( 4 )   419 - 424   2014

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    In micro-welding of aluminum alloy, its low melting point and high thermal conductivity make it difficult to obtain the large penetration depth with the good surface integrity. In order to perform the stable key-hole welding with little defects, it is important to understand the processing phenomenon near the boundary between heat conduction and key-hole type welding. Therefore, the boundary condition of key-hole generation in micro-welding of aluminum alloy was experimentally and numerically investigated with hybrid Nd:YAG laser system, in which a continuous diode laser (LD) of 808nm in wavelength was superposed in a pulsed Nd:YAG laser of 1064nm in wavelength. It became clear that the keyhole generation became stable when the continuous LD was superposed with pulsed Nd:YAG laser, and the shorter pulse interval time and higher continuous LD power led to the generation of the key-hole. The results of numerical analysis made it clear that the superposition of continuous diode laser is effective to stabilize the key-hole generation in micro-welding of aluminum alloy by pulsed Nd:YAG laser, since the continuous diode laser could keep the temperature near the boundary condition of key-hole generation appeared at the time when the temperature of welded bead was around the boiling point.

    DOI: 10.2493/jjspe.80.419

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  • Characterization of plasma in microwelding of glass using ultrashort laser pulse at high pulse repetition rates

    I. Miyamoto, Y. Okamoto, R. Tanabe, Y. Ito

    8TH INTERNATIONAL CONFERENCE ON LASER ASSISTED NET SHAPE ENGINEERING (LANE 2014)   56   973 - 982   2014

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    Dynamic behavior of plasma in internal modification of glass using fs-laser pulses with high pulse repetition rates up to 1MHz is observed using high-speed video camera at 50,000 frames per second. High-speed pictures reveal striking fact that the localized plasma is produced with size much smaller than reported in literatures before, and changes its location, size, shape and brightness periodically at repetition rates of the order of kHz. The mechanism responsible for producing localized plasma and its long-term periodic motion is presented based on the analysis of free -electron density based on rate equation. (C) 2014 Published by Elsevier B.V.

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  • Investigation of Micro-welding Characteristics of Si and Glass by Picosecond Pulsed Laser

    Imaduddin Helmin bin, Wan Nordin, Yasuhiro Okamoto, Isamu Miyamoto, Akira Okada

    Proceedings of the First Smart Laser Processing Conference 2014 (SLPC2014)   2014

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  • Investigation of Micro-drilling Characteristics for SiC by Harmonics of YAG Laser Reviewed

    URUSHIBATA Shin, OKAMOTO Yasuhiro, NAKASHIBA Shin-ichi, SAKAGAWA Tomokazu, OKADA Akira

    Proceedings of International Conference on Leading Edge Manufacturing in 21st century : LEM21   2013 ( 7 )   39 - 44   2013.11

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    Micro-drilling characteristics of SiC by harmonics of Nd:YAG laser were experimentally investigated in the viewpoints of wavelength and the surrounding gas type condition. Moreover, plasma and processing behavior were observed to discuss micro-drilling characteristics of SiC. The debris was removed away in the opposite direction of laser beam along the flow field generated by laser irradiation. The behavior, the spectrum and the intensity of laser induced plasma were influenced by the surrounding gas condition. The appearance of plasma affected the surface integrity at the circumference of drilled hole, and the surface integrity could be improved under the reduced pressure condition.

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  • Fundamental Characteristics of Spatter in Micro-drilling of Metal Sheet by Pulsed Nd:YAG Laser Reviewed

    SHIRASAYA Kento, OKAMOTO Yasuhiro, OKADA Akira

    Proceedings of International Conference on Leading Edge Manufacturing in 21st century : LEM21   2013 ( 7 )   45 - 50   2013.11

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    In laser cutting and drilling process, molten material was scattered as spatters, which deteriorate the surface integrity of workpiece due to the thermal damage. It is expected that the control of assist gas flow can reduce the adhesion of spatter. In order to investigate the improvement method of thermal damage due to the adhesion of spatter, it is required to clarify characteristics of spatters. Therefore, the collection and the analyzing method of spatters with high-speed video cameras in the laser micro-drilling were developed, and characteristics of spatter movement were numerically investigated by CFD analysis.

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  • Micro-welding of High Thermal Conductive Material Aluminum-Graphite Composite by Pulsed Nd:YAG Laser Reviewed

    Mohd Idris Shah Ismail, Yasuhiro Okamoto, Akira Okada, Yoshiyuki Uno, Muhaizad Muktar

    Journal of Laser Micro/Nanoengineering   8 ( 1 )   90 - 96   2013.2

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  • Fundamental study on sputter deposition of ceramic film by large-area electron beam irradiation Reviewed

    S. Misumi, A. Okada, Y. Okamoto, M. Inoue

    PROCEEDINGS OF THE SEVENTEENTH CIRP CONFERENCE ON ELECTRO PHYSICAL AND CHEMICAL MACHINING (ISEM)   6   486 - 491   2013

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    The sputter deposition of ceramic film on metal mold steel surface by large-area electron beam (EB) irradiation was discussed. The large-area EB has high energy density enough to generate plasma above the workpiece surface during the surface smoothing process, which causes the sputtering of target material set near the workpiece surface. The sputter deposition of target material with simultaneous surface melting and resolidification of workpiece surface by large-area EB would improve the adhesion between the deposited film and the workpiece. Short ceramic tube made of alumina or zirconia as a target was put on the substrate surface of steel, and large-area EB was irradiated to the surface. The workpiece surface component and structure after the irradiation were investigated using EDX and XRD analysis, in order to discuss the possibility of large-area EB irradiation as a new coating method. (C) 2013 The Authors. Published by Elsevier B.V.

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  • Neural network modeling for prediction of weld bead geometry in laser microwelding Reviewed

    Mohd Idris Shah Ismail, Yasuhiro Okamoto, Akira Okada

    Advances in Optical Technologies   ( 11 )   105 - 111   2013

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    Laser microwelding has been an essential tool with a reputation of rapidity and precision for joining miniaturized metal parts. In industrial applications, an accurate prediction of weld bead geometry is required in automation systems to enhance productivity of laser microwelding. The present work was conducted to establish an intelligent algorithm to build a simplified relationship between process parameters and weld bead geometry that can be easily used to predict the weld bead geometry with a wide range of process parameters through an artificial neural network (ANN) in laser microwelding of thin steel sheet. The backpropagation with the Levenberg-Marquardt training algorithm was used to train the neural network model. The accuracy of neural network model has been tested by comparing the simulated data with actual data from the laser microwelding experiments. The predictions of the neural network model showed excellent agreement with the experimental results, indicating that the neural network model is a viable means for predicting weld bead geometry. Furthermore, a comparison was made between the neural network and mathematical model. It was found that the developed neural network model has better prediction capability compared to the regression analysis model. © 2013 Mohd Idris Shah Ismail et al.

    DOI: 10.1155/2013/415837

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  • Influence of weld bead geometry on thermal deformation in laser micro-welding Reviewed

    S. Matsuoka, Y. Okamoto, A. Okada

    PROCEEDINGS OF THE SEVENTEENTH CIRP CONFERENCE ON ELECTRO PHYSICAL AND CHEMICAL MACHINING (ISEM)   6   492 - 497   2013

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    In this study, the thermal deformation of thin stainless steel sheet was investigated in the bead-on-plate welding by using a single-mode fiber laser with a Galvano scanning system. The numerical simulation was developed to calculate the temperature and stress fields, and its deformation characteristics were discussed. It was suggested that the specimen firstly deformed downward in the same direction of laser irradiation, and then deformed in the reversed direction after laser scanning. The final deformation angle in the negative direction, which is concave shape from the view direction of laser irradiation, was generated under the welding mode of conduction and quasi-penetration for 50 mu m thickness sheet. On the other hand, the positive angle of final deformation angle was obtained under full-penetration welding mode, and the extreme small distortion could be achieved by the proper weld bead geometry in micro-welding of thin sheet. It was also confirmed that the similar weld bead geometry was resulted in both quasi-penetration and full-penetration welding mode for 20 mu m thickness sheet, but the final deformation angle tendency was different in 50 mu m and 20 mu m specimen thickness. It was clarified that the welding deformation was influenced not only by weld bead geometry but also by specimen thickness. (C) 2013 The Authors. Published by Elsevier B.V.

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  • INVESTIGATION OF WIRE MOVEMENT IN FINE WIRE EDM BY HIGH-SPEED OBSERVATION Reviewed

    International journal of electrical machining   ( 18 )   43 - 48   2013

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  • Fundamental study on multi-wire EDM slicing of SiC by wire electrode with track-shaped section Reviewed

    A. Kimura, Y. Okamoto, A. Okada, J. Ohya, T. Yamauchi

    PROCEEDINGS OF THE SEVENTEENTH CIRP CONFERENCE ON ELECTRO PHYSICAL AND CHEMICAL MACHINING (ISEM)   6   232 - 237   2013

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    High efficient and precise slicing method is required for the slicing of silicon carbide ingot. The newly developed multi-wire electrical discharge slicing method would decrease the kerf width and the cracks generated on machined surface. However, much higher wire tension is required in order to reduce wire vibration and to perform a smaller kerf width. Thin wire electrode with round section does not have enough cross sectional area under the high wire tension condition. Therefore, a wire electrode with track-shaped section was proposed and applied to the wire EDM slicing of silicon carbide ingot. The running control of wire electrode with track-shaped section was experimentally investigated. The side support method with fixture plates could decrease the kerf width by brass coated steel wire electrode with track-shaped section. The parallel drawing type traverser and the short distance setting points of side support fixture plates could perform the smaller vibration of wire electrode with track-shaped section and the decrease of kerf width. (C) 2013 The Authors. Published by Elsevier B.V.

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  • Direct micro-joining of flexible printed circuit and metal electrode by pulsed Nd:YAG laser Reviewed

    Mohd Idris Shah Ismail, Yasuhiro Okamoto, Akira Okada, Yoshiyuki Uno, Kentaro Ueoka

    International Journal of Precision Engineering and Manufacturing   13 ( 3 )   321 - 329   2012.3

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    Laser micro-welding has proven to be a very successful tool for micro-joining in the electrical and electronic industries, where the miniaturization, the high strength and the high heat resistance are constantly requested. Recently, a flexible printed circuit (FPC) is expected as a new connection technology between electrical conductors according to the improvements of reliability and controllability with the diversification of the design concept. In this technology, it is required to weld a several tens μm thickness of FPC and a several hundreds μm thickness of metal electrode. This material combination accompanies the difficulty to control the welding phenomenon due to the differences of thermal property and heat capacity. As a good alternative, laser micro-welding has advantages of non-contact tool, low heat distortion and consistent weld integrity. In this study, the overlap welding of thin copper circuit on a polyimide film and a thick brass electrode was experimentally and numerically investigated by using a pulsed Nd:YAG laser. In addition, the shearing stress of overlap welding was evaluated with and without the control of pulse waveform, which can provide a well-directed controlling of the heat input with high energy density. The results showed that a porosity was observed as the major weld defect in the welding process without a pulse control. However, the appropriate controlled laser pulse configuration of micro-welding could remove the weld defects in the molten zone, improve the weld penetration stability and increase the weld strength. The potential benefits of controlled pulse waveform were discussed for the direct laser micro-welding process. It is clarified that the direct laser micro-welding of a thin copper circuit on a polyimide film and a thick brass electrode could be successfully achieved by appropriate controlled pulse waveform and heat input. © KSPE and Springer 2012.

    DOI: 10.1007/s12541-012-0041-3

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  • Micro-welding of Copper Plate by Frequency Doubled Diode Pumped Pulsed Nd:YAG Laser Reviewed

    Shin-ichi Nakashiba, Yasuhiro Okamoto, Tomokazu Sakagawa, Sunao Takai, Akira Okada

    LASER ASSISTED NET SHAPE ENGINEERING 7 (LANE 2012)   39   577 - 584   2012

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    A pulsed laser of 532 nm wavelength with ms range pulse duration was newly developed by second harmonic generation of diode pumped pulsed Nd:YAG laser. High electro-optical conversion efficiency more than 13% could welding be achieved, and 1.5 kW peak power green laser pulse was put in optical fiber of 100 mu m in diameter. In micro-welding of 1.0 mm thickness copper plate, a keyhole welding was successfully performed by 1.0 kW peak power at spot diameter less than 200 mu m. The frequency doubled pulsed laser improved the processing efficiency of copper welding, and narrow and deep weld bead was stably obtained. (C) 2012 Published by Elsevier B. V. Selection and/or review under responsibility of Bayerisches Laserzentrum GmbH

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  • Velocity and Angle of Spatter in Fine Laser Processing Reviewed

    Yasuhiro Okamoto, Hibiki Yamamoto, Akira Okada, Kento Shirasaya, Jari Tapani Kolehmainen

    LASER ASSISTED NET SHAPE ENGINEERING 7 (LANE 2012)   39   792 - 799   2012

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    Scattering velocity and angle of spatter were investigated by recognizing and tracking spatter with the high-speed video observation. The spatter movement was observed by two high-speed video cameras, and analyzed by twodirection tracking method, in which the 3D tracking lines of spatter were constructed in the forward and backward frames and the actual trajectory of individual spatter was obtained by averaging those tracking lines. It made clear that the initial velocity of spatter was less than the speed of sound and mainly ranged from 75m/s to 200m/s. The velocity of spatter showed the slight correlation with the angle. (C) 2012 Published by Elsevier B.V. Selection and/or review under responsibility of Bayerisches Laserzentrum GmbH

    DOI: 10.1016/j.phpro.2012.10.102

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  • Spatter Tracking in Laser Machining Reviewed

    Timo Viitanen, Jari Kolehmainen, Robert Piche, Yasuhiro Okamoto

    ADVANCES IN VISUAL COMPUTING, ISVC 2012, PT II   7432   626 - 635   2012

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    In laser drilling, an assist gas is often used to remove material from the drilling point. In order to design assist gas nozzles to minimize spatter formation, measurements of spatter trajectories are required.
    We apply computer vision methods to measure the 3D trajectories of spatter particles in a laser cutting event using a stereo camera configuration. We also propose a novel method for calibration of a weak perspective camera that is effective in our application.
    The proposed method is evaluated with both computer-generated video and video taken from actual laser drilling events. The method performs well on different workpiece materials.

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  • Optimization of Nozzle Flushing Method for Smooth Debris Exclusion in Wire EDM Reviewed

    Takuya Fujimoto, Akira Okada, Yasuhiro OKamoto, Yoshiyuki Uno

    PROCEEDINGS OF PRECISION ENGINEERING AND NANOTECHNOLOGY (ASPEN2011)   516   73 - +   2012

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    In a wire EDM using a thin wire electrode, better exclusion of debris from the machined kerf is important in order to maintain stable machining performance, since the area of spark generation is along a line and very small. When large amounts of debris stagnate in the gap, secondary discharges possibly occur and these discharges easily concentrate on the same location, which leads to unstable machining performance, wire breakage, low machining rate and a low shape accuracy.
    Conventionally, the exclusion of debris is carried out by jet flushing with an upper and lower nozzle. However, the flow field of machining fluid in the kerf due to the jet flushing and the effect of jet flushing conditions from the nozzles on debris exclusion have not yet been sufficiently examined. This study aims to clarify the flow field in the machined kerf by computational fluid dynamics (CM) and to propose new jet flushing methods for smooth debris exclusion in the wire EDM. The effects of workpiece thickness and machined kerf length on the flow field of working fluid in the kerf under conventional jet flushing conditions are discussed. Then, jet flushing with a tilting nozzle is proposed in order to decrease the debris stagnation area near the wire electrode. As a result, by using the tilting nozzle, removal rate can be improved because of the smooth debris exclusion.

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  • SURFACE MODIFICATION OF CEMENTED TUNGSTEN CARBIDE WITH NICKEL BINDER BY LARGE-AREA ELECTRON BEAM Reviewed

    Akira Okada, Shuhei Misumi, Yasuhiro Okamoto

    PROGRESS OF MACHINING TECHNOLOGY   207 - 210   2012

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    Cemented tungsten carbide with nickel binder is often applied to the metal mold for electronic parts due to its non-magnetic feature. However, it is difficult to use conventional methods applied to metal molds made of steel for the surface finishing or modification of cemented tungsten carbides in some cases. The large-area EB irradiation for conventional cemented tungsten carbide with cobalt binder was studied in our previous papers. In this paper, surface finishing and modification of cemented tungsten carbide with nickel binder were investigated, and the effects of EB conditions on the surface characteristics were discussed. The experimental results indicated that the surface roughness decreased and the surface glossiness increased by the large-area EB irradiation. Also, the water repellency and the releasability of molded resin from the surface could be improved under proper EB conditions.

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  • THERMAL DEFORMATION IN MICRO-WELDING OF THIN STAINLESS STEEL SHEET BY SINGLE-MODE FIBER LASER Reviewed

    Yasuhiro Okamoto, Satoshi Matsuoka, Mohd Idris Shah Ismail, Akira Okada

    PROGRESS OF MACHINING TECHNOLOGY   199 - 202   2012

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    In this study, the thermal deformation of thin stainless steel sheet in laser micro-welding were experimentally and numerically investigated. The welding deformation was experimentally evaluated using a single-mode CW fiber laser with a high-speed scanning system. The numerical simulation was developed to calculate the temperature, stress and deformation fields. It was clarified that the laser irradiation condition has a significant effect on the welding mode and stress field. In addition, the thermal deformation was influenced by the weld bead geometry and residual stress distributions, and the final deformation was formed by residual stress and plastic deformation. It was found that the tensile stress was generated around the molten zone and balanced by the compressive stress in the base material.

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  • HIGHT-SPEED OBSERVATION OF WIRE MOVEMENT IN FINE WIRE EDM Reviewed

    Sho Ichii, Akira Okada, Yasuhiro Okamoto

    PROGRESS OF MACHINING TECHNOLOGY   215 - 218   2012

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    In the wire EDM using a thin wire electrode, the reduction of wire vibration is important to achieve a high-precision machining, since large amplitude of wire vibration leads to large kerf width, low shape accuracy, rough machined surface and high risk of wire breakage. In this study, the movements of wire electrode are directly observed by using a high-speed video camera in order to clarify the wire vibration in fine wire EDM for thin workpiece. The results shows that the wire vibration amplitude during the process increases with wire running speed and flow rate of jet flushing but decreases with wire tension. Also, the wire behavior during process is almost 1st order string vibration. Furthermore, the wire vibration frequency increases with not only the wire tension but also the discharge pulse frequency.

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  • Singulation of Sapphire Substrate with High Aspect Ratio Internal Modification by Sub-nanosecond Pulsed Fiber Laser

    Yasuhiro Okamoto, Kenta Takahashi, Akira Okada

    Proceedings of 31st International Congress on Applications of Lasers & Electro-Optics 2012   813 - 819   2012

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  • Novel Fusion Welding Technology of Si/Glass Using Ultrashort Laser

    Isamu Miyamoto, Yashuhiro Okamoto, Jarno Kangastupa, Tiina Amberla, Assi Hansen, Jorma Vihinen

    Proceedings of 31st International Congress on Applications of Lasers & Electro-Optics 2012   784 - 793   2012

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  • Investigation on Micro-machining Characteristics and Phenomenon of Semiconductor Materials by Harmonics of Nd:YAG Laser

    Takayuki Hirano, Yasuhiro Okamoto, Akira Okada, Yoshiyuki Uno, Tomokazu Sakagawa, Shin-ichi Nakashiba

    PROCEEDINGS OF PRECISION ENGINEERING AND NANOTECHNOLOGY (ASPEN2011)   516 ( 516 )   36 - +   2012

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    Precision micro-machining without crack and heat affected zones is required in order to use high-performance materials such as silicon and silicon carbide, and it is expected that the higher harmonics of the Nd:YAG laser can perform precision micro-machining due to its high photon energy. However, even by using the harmonics of the Nd:YAG laser, a heat affected zone is inevitable due to the plasma generation. In order to reduce the influence of plasma on the processing results, it is important to understand the generation mechanism of plasma. Therefore, the laser induced plasma in micro-drilling of silicon carbide was observed by a high-speed shutter camera, and the influence of laser wavelength and surrounding conditions on the machining characteristics were experimentally investigated. The removal depth increased with decreasing wavelength and the surrounding gas pressure. The surface integrity was improved by the combination of shorter wavelength and reduced pressure conditions. The behavior of laser induced plasma was different from the wavelength of the laser beam and the surrounding gas pressure. Under atmospheric pressure conditions, the plasma grew greatly and affected the wider surface around the drilled hole with increasing wavelength. Under reduced pressure conditions, there was little difference in plasma size by wavelength, and the affected zone around the drilled hole became relatively smaller. It became clear. that a low surrounding gas pressure and shorter wavelength were important to obtain better surface integrity and highly efficient processing.

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  • Welding Characteristics of Foturan Glass Using Ultrashort Laser Pulses

    Isamu Miyamoto, Yasuhiro Okamoto, Kristian Cvecek, Michael Schmidt, Henry Helvajian

    Proceedings of 31st International Congress on Applications of Lasers & Electro-Optics 2012   775 - 783   2012

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  • Effects of Superposed Continuous Diode Laser on Welding Characteristics for Aluminum Alloy in Pulsed Nd:YAG Laser Welding

    Kazuya Miura, Yasuhiro Okamoto, Tomokazu Sakagawa, Yoshiyuki Uno, Shinichi Nakashiba

    JOURNAL OF LASER MICRO NANOENGINEERING   6 ( 3 )   225 - 230   2011.12

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    The efficient welding of aluminum alloy has been strongly required for lightening the electronic products and automobiles, and a pulsed Nd:YAG laser is widely used for its application. However, the low absorption of a Nd:YAG laser makes it difficult to weld the aluminum alloy efficiently. Therefore, a pulsed Nd:YAG laser of 1064nm in wavelength and a continuous diode laser of 808nm in wavelength were spatially superposed, since the absorption rate of the continuous diode laser to the aluminum alloy is much higher than that of a pulsed Nd:YAG laser. The maximum temperature of specimen surface in the vicinity of laser irradiation area increased 50K by the superposition of continuous diode laser and pulsed Nd:YAG laser, and the energy of Nd:YAG laser was absorbed efficiently. Moreover, the thermal analysis indicated that the temperature of specimen surface with the continuous diode laser and the pre-heating pulse could be kept approximately 200K higher than that without these processes. The combination of pre-heating pulse and diode laser made it possible to increase the penetration depth even from the beginning of laser scanning. DOI:10.2961/jlmn.2011.03.0010

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  • Characteristics of laser absorption and welding in FOTURAN glass by ultrashort laser pulses

    Isamu Miyamoto, Kristian Cvecek, Yasuhiro Okamoto, Michael Schmidt, Henry Helvajian

    OPTICS EXPRESS   19 ( 23 )   22961 - 22973   2011.11

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    The nonlinear absorptivity of FOTURAN glass to ultrashort laser pulses is evaluated by experimental measurement and thermal conduction model at different parameters including energy and repetition rate of the laser pulse, translation speed and thermal properties of the sample. The mechanical strength of an embedded laser-melted sample and an overlapped weld sample is determined by a three-point-bending test and a shear test, respectively. The results are related to the average absorbed laser power W-ab. We found the mechanical strength of an overlapped weld joint to be as high as that of the base material for low W-ab, if the sample pair is pre-bonded to provide optical contact. (C) 2011 Optical Society of America

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  • Surface modification of cemented carbide by EB polishing

    A. Okada, R. Kitada, Y. Okamoto, Y. Uno

    CIRP ANNALS-MANUFACTURING TECHNOLOGY   60 ( 1 )   575 - 578   2011

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    Cemented carbide has many excellent properties. However, it is sometimes difficult to apply conventional surface finishing or surface modification methods for the cemented carbide. The possibility of surface modification by large-area electron beam irradiation, namely EB polishing was discussed. The surface structure of the EB polished cemented carbide was observed by TEM. The hardness and the water repellency were tested. Also, the separation force of molded resin from the surface was measured for evaluating the releasability of the resin. The water repellency and the releasability of the molded resin could be improved by EB polishing, because the surface structure changed. (C) 2011 CIRP.

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  • Effect of Continuous Diode Laser on Crack Generation in Pulsed Nd:YAG Laser Welding of Aluminum Alloy

    Kazuya MIURA, Yasuhiro OKAMOTO, Shin-ichi NAKASHIBA, Tomokazu SAKAGAWA, Akira OKADA, Yoshiyuki UNO

    Proceedings of the 6th International Conference on Leading Edge Manufacturing in 21st Century   2011

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  • Clarification of Surface Layer Temperature in EB Polishing by Unsteady Heat Conduction Analysis Reviewed

    Tomohiro FUJITA, Akira OKADA, Yasuhiro OKAMOTO, Yoshiyuki UNO

    Proceedings of the 6th International Conference on Leading Edge Manufacturing in 21st Century   2011

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  • Influence of Carbon Fiber Direction on EDM Characteristics of CFRP

    Sho ICHII, Akira OKADA, Yasuhiro OKAMOTO, Yoshiyuki UNO

    Proceedings of the 6th International Conference on Leading Edge Manufacturing in 21st Century   2011

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  • Effects of Laser Wavelength and Intensity Distribution on Removal Characteristics of TCO Film

    Naoya TAKAHASHI, Yasuhiro OKAMOTO, Shin-ichi NAKASHIBA, Tomokazu SAKAGAWA, Akira OKADA, Yoshiyuki UNO

    Proceedings of the 6th International Conference on Leading Edge Manufacturing in 21st Century   2011

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  • High-quality Dicing of Semiconductor Package by Superposition of Pulsed Fiber Laser and SHG:YAG Laser

    Hibiki YAMAMOTO, Yasuhiro OKAMOTO, Muhamad Fahmi, bin Mohd Noor, Ryouji KITADA, Akira OKADA

    Proceedings of the 6th International Conference on Leading Edge Manufacturing in 21st Century   2011

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  • Welding Characteristics of Aluminum Alloy by Pulsed Nd:YAG Laser with Pre- and Post-irradiation of Superposed Continuous Diode Laser

    Shin-ichi Nakashiba, Yasuhiro Okamoto, Tomokazu Sakagawa, Kazuhiro Miura, Akira Okada, Yoshiyuki Uno

    Proceedings of 28th International Congress on Applications of Lasers & Electro-Optics 2011   825 - 832   2011

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  • Experimental Investigation on Micro-welding of Thin Stainless Steel Sheet by Fiber Laser

    Mohd Idris Shah Ismail, Yasuhiro Okamoto, Akira Okada, Yoshiyuki Uno

    American Journal of Engineering and Applied Sciences   4 ( 3 )   306 - 312   2011

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  • Fusion welding characteristics of FOTURAN glass using ultrashort laser pulses

    Isamu Miyamoto, Kristian Cvecek, Yashuhiro Okamoto, Michael Schmidt, Henry Helvajian

    Proceedings of 12th International Symposium on Laser Precision Microfabrication   On-line #10-74   2011

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  • Numerical Simulation on Micro-welding of Thin Stainless Steel Sheet by Fiber Laser

    ISMAIL Mohd Idris Shah, OKAMOTO Yasuhiro, UNO Yoshiyuki

    ( 16 )   9 - 14   2011

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  • Fundamental Study on High-quality Dicing Method for Semiconductor Package by Fiber Laser Reviewed

    Ryoji Kitada, Yasuhiro Okamoto, Yoshiyuki Uno, Takuya Ikeda

    PROCEEDINGS OF THE 16TH INTERNATIONAL SYMPOSIUM ON ELECTROMACHINING, 2010   425 - 429   2010

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    Recently, the laser dicing method has been expected to replace a blade dicing method because of its high flexibility. However, in the laser dicing, the heat affected zone yielding heat damage should be reduced in order to prevent the deterioration of semiconductor devices consisting of silicon chip. Therefore, the reduction of heat affected zone was experimentally investigated by using cooled assist gas. It is clarified that the combination of nitrogen assist gas in the coaxial direction of laser beam and cooled assist gas from the rear side of cutting direction led to the better cutting results with low heat affected zone.

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  • Investigation on Welding Phenomenon for Aluminum Alloy by Superposition of Pulsed YAG Laser and Diode Laser

    Shin Haraguchi, Yasuhiro Okamoto, Yoshiyuki Uno, Tomokazu Sakagawa, Shin-ichi Nakashiba

    JOURNAL OF ADVANCED MECHANICAL DESIGN SYSTEMS AND MANUFACTURING   4 ( 5 )   875 - 882   2010

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    A pulsed Nd:YAG laser and a continuous diode laser were spatially superposed for higher absorption of laser beam to aluminum alloy. 12-20% increase in the bead width and 15-30% increase in the weld depth could be obtained by the superposition of continuous diode laser and pulsed Nd: YAG laser. Moreover, the unsteady thermal analysis with a key-hole effect indicated that the temperature of specimen surface with a continuous diode laser could be kept approximately 300K higher than that without a continuous diode laser. Therefore, it was clarified that the bead width and depth would increase greatly due to higher absorption of Nd: YAG laser to aluminum alloy by the superposition of a continuous diode laser.

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  • Observation of Plasma Behavior in Micro-machining of Ceramics by Harmonics of Nd:YAG Laser

    Norihiro Hayashi, Yasuhiro Okamoto, Yoshiyuki Uno, Tomokazu Sakagawa

    JOURNAL OF ADVANCED MECHANICAL DESIGN SYSTEMS AND MANUFACTURING   4 ( 5 )   867 - 874   2010

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    Precision micro-machining without cracks and with a narrow heat affected zone is highly required for the effective use of high-performance material. For this purpose, it is expected that the higher harmonics of Nd:YAG laser could perform the precision micro-machining by its high photon energy. However, even using harmonics of Nd: YAG laser, the heat affected zone is inevitable due to the plasma generation. In order to reduce the influence of plasma, it is important to understand the generation mechanism of plasma. Therefore, the laser induced plasma was observed by the high-speed shutter camera, and the influence of laser wavelength on machining characteristics was investigated.

    DOI: 10.1299/jamdsm.4.867

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  • Fundamental Study on Micro-welding of Thin Stainless Steel Sheet by Fiber Laser

    M. I. S. Ismail, Y. Okamoto, Y. Uno

    PROCEEDINGS OF THE 16TH INTERNATIONAL SYMPOSIUM ON ELECTROMACHINING, 2010   431 - 435   2010

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    In this study, the characteristics of laser micro-welding with a high-speed scanning system on thin stainless steel sheets by using a single-mode CW fiber laser were experimentally investigated. It was clarified that the welding bead width and depth increased when increasing the scan velocity under a constant energy density condition, and high efficient welding was expected by using high-speed laser scanning with Galvano scanner. The utilization of assist gas is found to be very effective to obtain smooth fusion bead. In addition, the combination of micro beam spot and high-speed laser scanning made it possible to obtain good overlap welding of ultra-thin stainless steel sheets.

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  • High Quality Laser Dicing of Semiconductor Package with a Single-mode Q-switched Fiber Laser

    KITADA Ryoji, OKAMOTO Yasuhiro, UNO Yoshiyuki, IKEDA Takuya

    ( 15 )   33 - 38   2010

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  • Novel fusion welding technology of glass using ultrashort pulse lasers

    Aisamu Miyamoto, Kristian Cvecek, Yasuhiro Okamoto, Michael Schmidt

    LASER ASSISTED NET SHAPE ENGINEERING 6, PROCEEDINGS OF THE LANE 2010, PART 1   5 ( 5 )   483 - 493   2010

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    A novel fusion welding technology of glass using ultrashort laser pulses with high pulse repetition rates has been developed, where the laser energy is selectively absorbed at the interface by nonlinear process to provide crack-free welding without pre- and post-heating. A laser-matter interaction model is developed to evaluate the distribution of the ultrashort pulse laser energy absorbed in bulk glass. A thermal conduction equation is derived to calculate transient 3-dimensional temperature distribution and dimensions of molten zone in glass. The mechanical strength of weld joint is evaluated taking into consideration of the attracting force of the optical contact between the glass plates needed for keeping the high-temperature plasma in the bulk glass. (C) 2010 Published by Elsevier B.V.

    DOI: 10.1016/j.phpro.2010.08.171

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  • Direct Joining of FPC and Metal Electrode by Pulsed Nd:YAG Laser

    Mohd Idris Shah Ismail, Yasuhiro Okamoto, Yoshiyuki Uno

    Proceedings of 27th International Congress on Applications of Lasers & Electro-Optics 2010   2010

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  • E18 Investigation on Welding Phenomenon for Aluminum Alloy by Superposition of Pulsed YAG Laser and Diode Laser(Laser processing)

    HARAGUCHI Shin, OKAMOTO Yasuhiro, UNO Yoshiyuki, SAKAGAWA Tomokazu, NAKASHIBA Shin-ichi

    Proceedings of International Conference on Leading Edge Manufacturing in 21st century : LEM21   2009 ( 5 )   573 - 576   2009.12

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    Pulsed Nd:YAG laser and continuous diode laser were spatially superposed for higher absorption to aluminum alloy. 12-20% increase in bead width and 15-30% increase in weld depth could be obtained by superposition of continuous diode laser and pulsed Nd:YAG laser. Moreover, the unsteady thermal analysis with key-hole effect indicated that the temperature of specimen surface with continuous diode laser could be kept approximately 300K higher than that without continuous diode laser. Therefore, it was clarified that the bead width and depth would increase greatly due to higher absorption of Nd:YAG laser to aluminum alloy by superposition of diode laser.

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  • E21 Observation of Plasma Behavior in Micro-machining of Ceramics by Harmonics of Nd:YAG laser(Laser processing)

    HAYASHI Norihiro, OKAMOTO Yasuhiro, UNO Yoshiyuki, SAKAGAWA Tomokazu

    Proceedings of International Conference on Leading Edge Manufacturing in 21st century : LEM21   2009 ( 5 )   585 - 588   2009.12

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    Precision micro-machining without crack and with narrow heat affected zone is required in order to use high-performance material. For this purpose, it is expected that higher harmonics of Nd:YAG laser could perform precision micro-machining by its high photon energy. However, even using harmonics of Nd:YAG laser, heat affected zone is inevitable due to the plasma generation. In order to reduce the influence of plasma, it is important to understand the generation mechanism of plasma. Therefore, the laser induced plasma was observed by high-speed shutter camera, and the influence of laser wavelength on machining characteristics was investigated.

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  • High Efficiency and High Quality Welding of Aluminum Alloy by Hybrid System Combined Nd:YAG Laser and Diode Laser

    酒川友一, 小市真樹, 加藤悦史, 中芝伸一, 原口心, 岡本康寛, 宇野義幸

    精密工学会誌(CD-ROM)   75 ( 10 )   1222 - 1226   2009.10

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    Recently the welding of aluminum alloy has been strongly required for the lightening the electronic products, the automobiles and so on. Then the hybrid laser system was newly developed in order to perform the high efficiency and high quality welding of aluminum alloy. The high electric-optical conversion efficiency was achieved by the new diode pumped pulsed Nd:YAG laser. The hybrid system is consisted of a newly developed pulsed Nd:YAG laser and a continuous diode laser, and it can deliver two lasers by one fiber. Higher absorption of laser energy into the aluminum alloy can be expected under the continuous irradiation of diode laser (λ= 808 nm), since the absorption into aluminum alloy shows the maximum at λ= 850 nm. The suitable bead width and depth could be obtained with better surface integrity when the pulse waveform took the highest peak at the first period. The bead width and depth increased with increasing the power of continuous diode laser, which leads to overlapping welding even under high speed condition. Moreover, the high efficiency and high quality welding of aluminum battery case could be accomplished by the newly developed hybrid system, in which the suitable pulse energy and the peak power could be given even under the high pulse repetition rate.

    DOI: 10.2493/jjspe.75.1222

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  • Investigation of Surface Treatment Method by High-speed Scanning of Single-mode Fiber Laser with MOPA Reviewed

    Yasuhiro Okamoto, Yoshiyuki Uno, Tetsuomi Mohri, Taito Izawa

    PROGRESS OF MACHINING TECHNOLOGY   407-408   624 - 627   2009

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    A newly surface treatment method was proposed by the combination of the high-speed laser scanning with Galvano scanner and the single-mode pulsed fiber laser with Master Oscillator Power Amplifier, and various periodic structures could be formed by this technique. The surface roughness of irradiated area increased almost proportionally with increasing the number of laser scan, and it could be controlled by the number of scan. The repellency of surface could be increased by the laser irradiation compared to that of ground surface under nitrogen atmosphere condition, while the hydrophilic property of surface could be improved by the laser scanning under air atmosphere condition. Moreover, it was found that the corrosion resistance of the surface could be improved by laser irradiation.

    DOI: 10.4028/www.scientific.net/KEM.407-409.624

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  • High-efficiency Welding of Aluminum Alloy by Hybrid System Combined pulsed Nd:YAG Laser and Diode Laser Reviewed

    Tomokazu SAKAGAWA, Yasuhiro OKAMOTO, Yoshiyuki UNO, Shin HARAGUCHI, Shin-ichi NAKASHIBA

    Proceedings of 26th International Congress on Applications of Lasers & Electro-Optics 2009   1008 - 1014   2009

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  • Evaluation of Molten Zone in Glass Welding Using Ultra-short Pulsed Laser

    Zazuli Bin Mohid, Yasuhiro Okamoto, Keishi Yamamoto, Yoshiyuki Uno, Isamu Miyamoto, Kristian Cvecek, Michael Schmidt, Peter Bechtold

    Proceedings of International Conference on Leading Edge Manufacturing in 21st Century   569 - 572   2009

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  • Effect of Nozzle Shape on Dross Generation in Fine Cutting of Thin Metal Plate by Pulsed Nd:YAG Laser

    Hiroshi SUZUKI, Yasuhiro OKAMOTO, Yoshiyuki UNO

    Proceedings of International Conference on Leading Edge Manufacturing in 21st Century   577 - 580   2009

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  • Laser-matter interaction in fusion welding of fused silica using ultrashort laser pulses

    I. Miyamoto, K. Cvecek, Y. Okamoto, P. Bechtold, M. Schmidt

    Proceedings of LAMP2009   #108   2009

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  • Fusion welding technology of glass based on new concept using ultrashort pulse

    Isamu Miyamoto, Kristian Cvecek, Yasuhiro Okamoto, Peter Bechtold, Michel Schmidt, Thomas Hermanns

    Proceedings of the Fifth International WLT-Conference on Lasers in Manufacturing 2009   741 - 748   2009

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  • Investigation on Multi-wire EDM Slicing Method for Polycrystalline Silicon Ingot Reviewed

    Hirokazu Takahashi, Yasuhiro Okamoto, Yoshiyuki Uno, Akira Okada, Yoshihiro Abe, Shiro Takata

    Proceedings of 3rd International Conference of Asian Society for Precision Engineering and Nanotechnology   1C-15-1873   2009

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  • Influence of Polarization Plane on Groove Shape in Scribing of Sapphire by THG:YAG Laser Reviewed

    Yasuhiro Okamoto, Tomokazu Sakagawa, Yoshiyuki Uno, Yutaka Mukoya, Yuki Okamura

    Proceedings of 26th International Congress on Applications of Lasers & Electro–Optics 2009   1080 - 1085   2009

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  • Effect of Nozzle Shape on Fine Cutting of Thin Steel Plate by Pulsed Nd:YAG Laser

    Y. Okamoto, Y. Uno, H. Suzuki

    Proceedings of LAMP2009   2009

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  • Fine Micro-welding of Thin Stainless Steel Sheet by High Speed Laser Scanning Reviewed

    Yasuhiro Okamoto, Arnold Gillner, Alexander Olowinsky, Jens Gedicke, Yoshiyuki Uno

    JOURNAL OF LASER MICRO NANOENGINEERING   3 ( 2 )   95 - 99   2008.4

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    Fraunhofer Institute for Laser Technology had developed the SHADOW (R) welding technique, in which high speed joining with minimal distortion is possible using a pulsed Nd:YAG laser. The possibility of high speed, high quality welding had been also reported by use of a single-mode fiber laser. The combination of micro-beam and high speed laser scanning offers potential advantages for thin metal sheet welding. Therefore, the characteristics of micro-welding for thin stainless sheet were investigated here by high speed laser scanning with both single-mode fiber laser and pulsed Nd: YAG laser. The results were a narrow welding region obtained using a laser beam with a large focus diameter of 160 mu m without pulse control, while a small focus diameter of 22 mu m was found in general to provide good control of the welding state. A small focus diameter can result in an excellent welding seam from the start, even without pulse control. The penetration depth could be controlled by the energy density with a small focus diameter. For the smaller beam foucus diameter, an unique periodic structure appeared at high beam scanning velocities. Moreover, by using a laser beam with a small focus diameter, the overlap welding of 25 mu m thickness sheet could be successfully performed, regardless of the presence of a small gap distance between two sheets.

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  • Influence of Irradiation Method on Laser Forming Characteristics of Plastics "jointly worked"

    Yasuhiro OKAMOTO, Yoshiyuki UNO, Zazuli MOHID, Yoshiharu NAMBA

    Proceedings of 2nd International Workshop on Thermal Forming   385 - 393   2008

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  • Micro-welding of Stainless Steel Foil by High Speed Laser Scanning Reviewed

    Yasuhiro Okamoto, Arnold Gillner, Alexander Olowinsky, Jens Gedicke, Yoshiyuki UNO

    The Paton Welding Journal   158 - 162   2008

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  • Development of Multi-wire EDM Slicing Method for Silicon Ingot

    Yasuhiro Okamoto, Yoshiyuki Uno, Akira Okada, Satoru Ohshita, Tameyoshi Hirano, Shiro Takata

    Proceedings of ASPE 2008 Annual Meetingnand the 12th ICPE   503 - 533   2008

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  • Temperature Distribution and Bending Characteristics in Plastics Laser Forming

    Zazuli bin Mohid, Yasuhiro OKAMOTO, Yoshiyuki UNO, Shunsuke TANAKA, Naoki CHUJO, Yoshiharu NAMBA

    Proceedings of International Conference on Mechanical and Manufacturing Engineering 2008   MFG_ID_0027-1-MFG_ID_0027-5   2008

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  • Cutting of Solid Type Molded Composite Materials by Q-switched Fiber Laser with High-Performance Nozzle

    Yasuhiro Okamoto, Ryoji Kitada, Yoshiyuki Uno, Hiroyuki Doi

    JOURNAL OF ADVANCED MECHANICAL DESIGN SYSTEMS AND MANUFACTURING   2 ( 4 )   651 - 660   2008

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    This paper deals with the effects of the nozzle shape on cutting results and fundamental characteristics of laser cutting of solid type molded composite materials, which was composed of semiconductor board and epoxy-resin molding compounds, by Q-switched single-mode fiber laser. Experimental results clarified that high speed cutting of 16 mm/s could be carried out using a Laval throat nozzle with initial expansion zone, which also led to straighter kerf shape and narrower kerf width than other nozzles. Besides, Laval throat nozzle made it possible to reduce the kerf width, and the difference of kerf width between irradiation-side and exit-side became smaller. Nitrogen assist gas led to the narrow kerf width and straight kerf shape. Furthermore, the difference of kerf between substrate side and epoxy-resin side became smaller. Substrate side irradiation was more suitable for precision cutting than epoxy-resin side irradiation. These results proved that Q-switched single-mode fiber laser was useful for cutting of composite materials.

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  • Novel Fusion Welding Technology of Glass Using Ultrashort Pulse Lasers

    Isamu Miyamoto, Alexander Horn, Jens Gottmann, Dirk Wortmann, Ilja Mingareev, Fumiyo Yoshino, Michael Schmidt, Peter Bechtold, Yasuhiro Okamoto, Yoshiyuki Uno, Thomas Herrmann

    Proceedings of 25th International Congress on Applications of Lasers & Electro-Optics 2008   112 - 121   2008

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  • Laser beam micro joining - new processes and applications

    Alexander Olowinsky, Jens Gedicke, Andre Boglea, Arnold Gillner, Yasuhiro Okamoto

    Proceedings of Lasers in Manufacturing LIM 2007   651 - 657   2007

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  • Multi-wire Slicing Method for Silicon Ingot with Electrical Discharge Machining

    Satoru Ohshita, Yoshiyuki Uno, Akira Okada, Yasuhiro Okamoto, Tameyoshi Hirano, Shiro Takata

    Proceedings of Asian Electrical Machining Symposium '07   126 - 129   2007

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  • Micro-machining Characteristics of Ceramics by Harmonics of Nd:YAG Laser

    Hikaru NAKAMURA, Yasuhiro OKAMOTO, Yoshiyuki UNO

    Proceedings of International Conference on Leading Edge Manufacturing in 21st Century   849 - 852   2007

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  • Fine micro-welding of thin metal sheet by high speed laser scanning

    Yasuhiro Okamoto, Arnold Gillner, Alexander Olowinsky, Jens Gedicke, Yoshiyuki Uno

    PHOTONIC MATERIALS, DEVICES, AND APPLICATIONS II   6593   65930D-1-65930D-10   2007

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    Recently, since the size of component becomes smaller, then the welding of thin metal sheet has been required. Besides, the flexibility of process is important according to the accessibility especially for small components. Fraunhofer Institute for Laser Technology had developed the SHADOW((R)) welding technology, in which the high speed joining with small distortion is possible using pulsed Nd:YAG laser. The possibility of high speed and high quality welding had been reported by using single-mode fiber laser. The combination of micro beam and high speed laser scanning has the advantages for thin metal sheet welding. Therefore, the characteristics of micro-welding for thin metal sheet were investigated by high speed laser scanning, in which the welding was carried out by high speed scanner system with single-mode fiber laser and pulsed Nd:YAG laser. The proper welding region was narrow by the laser beam with a large focus diameter of 160 mu m without pulse control, while a small focus diameter of 22 mu m can control the welding state widely. A small focus diameter can perform the excellent welding seam from the extreme beginning without pulse control. The penetration depth can be controlled by the energy density with a small focus diameter of 22 mu m at the energy densities less than 1 J/mm(2). Besides, the unique periodic structure appeared at the high velocity of beam scanning with a small focus diameter. Moreover, the overlap welding of 25 mu m thickness sheet can be performed regardless of small gap distance between two sheets by the laser beam with a small focus diameter of 22 mu m.

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  • Cutting of Solid Type Molded Composite Materials by Q-switched Fiber Laser with High-performance Nozzle

    Hiroyuki DOI, Yasuhiro OKAMOTO, Yoshiyuki UNO, Ken Shiwayama, Ryoji KITADA

    Proceedings of International Conference on Leading Edge Manufacturing in 21st Century   853 - 856   2007

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  • Micro Cutting of Thin Copper Plate by Fiber Laser with Laval Nozzle

    Yasuhiro Okamoto, Norio Kataoka, Hirokazu Tahara, Ken Shiwayama, Yoshiyuki Uno

    JOURNAL OF LASER MICRO NANOENGINEERING   1 ( 3 )   243 - 246   2006.12

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    Fiber laser has many advantages such as compact size, high conversion efficiency, good beam mode, air cooling and maintenance free. Therefore, it has high possibility as an industrial light source in the near future. The beam from fiber laser can be focused in a micro spot because of its excellent beam quality. However, the narrow kerf leads to the difficulty of outflow of melted material. Therefore, micro cutting by a single-mode fiber laser is considerably difficult, then the high performance nozzles are strongly required. In the previous work, authors developed a high performance nozzle, which can increase the velocity of assist gas flow and makes it possible to reduce the dross in the micro kerf. Therefore, high performance cutting by a single-mode fiber laser can be expected by using our newly designed nozzle. In this study, the effect of nozzle shape on the machining results in precision cutting of thin copper plate by a Q-switched single-mode fiber laser was experimentally investigated. It was found that the high speed cutting at 30mm/s could be carried out by the high performance nozzle under low pulse frequency condition. Besides, the reduction of the dross and good kerf shape could be attained in the case of nitrogen assist gas.

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  • Cutting characteristics of thin copper plate by Q-switched single-mode fiber laser with high-performance nozzle

    Ken Shiwayama, Yoshiyuki Uno, Yasuhiro Okamoto

    Progress of Machining Technology, Proceedings   365 - 368   2006

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    The fundamental characteristics of laser cutting for thin copper plate by a Q-switched single-mode fiber laser were experimentally investigated, and the effects of the nozzle shape on cutting results are also discussed. In the case of traditional convergent nozzle with nitrogen assist gas, it was impossible to cut under any experiment condition, since assist gas pressure on workpiece was lower. On the other hand, high speed cutting of 30mm/s could be carried out using high-performance Nozzle Laval 800 and Nozzle Laval 800 IEZ, since high assist gas pressure could be supplied on the workpiece. In addition, the dross height using Nozzle Laval 800 and Nozzle Laval 800 IEZ was very small less than 10um, and the very narrow kerf and straight cut shape could be obtained. Therefore Q-switched single-mode fiber laser with high-performance nozzles proved to be useful for cutting of thin copper plate.

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  • Effect of Laser Wavelength on Machining Characteristics of Aluminum Nitride in Micro-boring

    Norio Kataoka, Yasuhiro Okamoto, Yoshiyuki Uno, Itaru Tanino

    Proceedings of 25rd International Congress on Applications of Lasers & Electro–Optics 2006   2006

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  • Microboring of Fine Powder Cemented Carbide Using Diode-pumped Q-switched YAG Laser

    OKAMOTO Yasuhiro, KATAOKA Norio, UNO Yoshiyuki, YUASA Eiji, KUBOTA Shin-ichiro

    Journal of the Japan Society of Electrical-machining Engineers.   40 ( 93 )   21 - 28   2006

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  • Precision Cutting of Thin Plate of Copper by Single Mode Fiber Laser with Newly Designed Nozzle(Laser processing)

    TAHARA H., UNO Y., OKAMOTO Y., SHIWAYAMA K.

    Proceedings of International Conference on Leading Edge Manufacturing in 21st century : LEM21   2005 ( 1 )   273 - 278   2005

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    The fundamental characteristics of laser cutting for thin copper plate by a Q-switched single-mode fiber laser were experimentally investigated, and the effects of the nozzle shape on cutting results were also discussed. High speed cutting of 29mm/s could be carried out with a newly designed nozzle, since high assist gas pressure could be supplied on the workpiece without MSD. Nozzle Laval 800 makes it possible to cut more efficient, since the melted material in the kerf decreases compared to a traditional convergent nozzle. Using a Q-switched single-mode fiber laser, the kerf is very fine, and color change around the kerf is hardly observed by oxidation due to little heat conduction from dross. Therefore, it proved to be available in cutting of thin metal plate.

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  • Fundamental Study on Multi-wire EDM Slicing Method for Monocrystalline Silicon Ingot-Effects of Supply Method of Working Fluid and Wire Speed on Machining Characteristics- Reviewed

    UNO Yoshiyuki, OKADA Akira, OKAMOTO Yasuhiro, SUZUKI Katsutomo, HIROTA So, HIRANO Tameyoshi, TAKATA Shiro, ISHIKAWA Kazuhiko

    Proceedings of International Conference on Leading Edge Manufacturing in 21st Century, 2005   783   783 - 786   2005

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    A new slicing method of monocrystalline silicon ingot using wire electrical discharge machining was proposed for high efficiency and high quality slicing instead of inner diameter blade or multi-wire method. The effects of supply method of working fluid and wire speed on machining characteristics were experimentally investigated. It is clarified that the immersion method is superior than the nozzle supply method and the wire speed over 200m/min is desirable for stable machining. Besides, mounting of wire sub-guide is useful for obtaining better kerf shape.

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  • Nd:YAG高調波レーザによる窒化アルミニウムの微細穴加工

    岡本康寛, 片岡範生, 宇野義幸

    電気加工技術   29(92), 8-13 ( 92 )   8 - 13   2005

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  • Effects of Nozzle Shape on Precision Micro Cutting of Thin Metal Plate by Pulsed YAG Laser

    岡本康寛, 宇野義幸, 村上義文, 細萱正義, 三柳直毅

    精密工学会誌   70 ( 2 )   246 - 250   2004.2

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    In YAG laser cutting process of thin plate, it is important to understand the assist gas flow from the tip of a convergent nozzle in order to improve the machining accuracy, since melted material is mostly carried away downward by the gas flow. Besides, it is considered that the nozzle shape influences the assist gas flow. In this paper, the effects of the nozzle shape on assist gas flow and machining results in micro machining by a pulsed YAG laser are experimentally investigated. There is an unstable region where the pressure on a workpiece changes periodically regardless of the internal shape and exit diameter of nozzle. The unstable region starts at low cylinder gas pressure and becomes smaller in range with increasing the exit diameter. Under middle and high cylinder gas pressure conditions over 300kPa, height of dross becomes smaller with the increase of the exit diameter for a nozzle of conical internal shape, since the pressure on workpiece increases. Furthermore, when the conical inner wall of nozzle is changed to a convex inner wall, it is possible to reduce the height of dross. Additionally, the height of dross becomes lower, when the curvature of the inner wall increases under the high pressure condition.

    DOI: 10.2493/jspe.70.246

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  • Laser Forming of Plastic by YAG Laser. Invited

    岡本康寛, 宮本勇, 宇野義幸

    高温学会誌   30 ( 1 )   47 - 54   2004.1

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    In this study, the effect of the laser beam irradiation method on the deformation characteristics of laser forming for plastic material by YAG laser was experimentally investigated. In the case of area irradiation method, bending angle becomes smaller after the irradiation, since the amount of bending-down is large during the irradiation. Therefore, even if the number of laser beam irradiation increases, large bending angle can not be obtained. On the other hand, in the case of scan irradiation method, the bending angle becomes larger after the irradiation, since the amount of bending-down is small during the irradiation. As a result, the scan irradiation method makes it possible to obtain large bending angles up to 90 degrees by increasing the number of laser scan. Therefore, in order to obtain larger bending angles, the scan irradiation method is more effective than the area irradiation method.

    DOI: 10.7791/jhts.30.47

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  • Precision Micro Cutting of Thin Steel Plate with Newly Designed Laval Nozzle by Pulsed YAG Laser

    Yasuhiro OKAMOTO, Yoshiyuki UNO, Masayoshi HOSOGAYA, Naoki MIYANAGI

    Proceedings of 23rd International Congress on Applications of Lasers & Electro–Optics 2004, M204,Precision Drilling & Cutting   2004

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  • Deformation characteristics of plastics in YAG laser forming

    Y Okamoto, Miyamoto, I, Y Uno, T Takenaka

    FIFTH INTERNATIONAL SYMPOSIUM ON LASER PRECISION MICROFABRICATION   5662   576 - 581   2004

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    Plastic material can be also bent by laser forming in the same way as metal material, and larger bending angle can be obtained as compared to metal material. However, its deformation mechanism has not been yet clarified. Therefore, in this study, the machining characteristics and the deformation mechanism of plastic in YAG laser forming were made clear by experimental and numerical analysis. Small temperature gradient was obtained by thermal analysis in laser forming of high density polyethylene. The plastic material could be bent due to high viscoelasticity in spite of small temperature gradient. Specimen was first bent by the temperature gradient in thickness direction in a few seconds after the laser irradiation. Then, the temperature of specimen became almost the same in thickness direction, and the temperature gradient appeared only in side direction. Therefore, the deformation of specimen was occurred by the contraction of specimen in side direction and the effect of initial shape, which was deformed by the temperature gradient just after the laser irradiation. Besides, it was clarified that small thermal conductivity of plastic material lead to low cooling speed. Therefore, sufficient cooling time is necessary in order to control the deformation accurately, since the temperature of specimen should be kept equal before every laser irradiation.

    DOI: 10.1117/12.596567

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  • 「文鎮」から「ジャイロスコープ」へ進化した「機械工作実習」

    宇野義幸, 岡田晃, 岡本康寛

    工学教育   51 ( 5 )   58 - 61   2003.9

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    In the Department of Mechanical Engineering at Okayama University, the manufacturing practice has been taken as an important subject, not only for educational manufacturing practice but also for introducing "Hands-on" fabrication. Therefore, this class was shifted from the second to the first grade year. Furthermore, the manufacturing of a simple shaped paperweight was altered to a complicated product, gyroscope. The analysis of questionnaire shows that the improvements in the subject are very effective in student's motivation for Hands-on fabrication. We hope that this subject will be a trigger for students to develop a creative ability.

    DOI: 10.4307/jsee.51.5_58

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  • Laser Forming of Plastic by YAG Laser

    Yasuhiro OKAMOTO, Yoshiyuki UNO, Yoshiharu NAMBA

    Proceedings of International Conference on Laser Technologies in Welding and Materials Processing   2003

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  • 513 Effect of Laval Nozzle in Precision Cutting of Thin Metal Plate by Pulsed YAG Laser

    Okamoto Y., Uno Y., Hosogaya M., Miyanagi N.

    Proceedings of International Conference on Leading Edge Manufacturing in 21st century : LEM21   2003   915 - 920   2003

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    Effects of Laval nozzle on assist gas flow and the machined results in precision cutting of thin plate by pulsed YAG laser were experimentally investigated. Assist gas flow from Laval nozzle does not have Mach Shock Disk, and goes more straight than a traditional convergent nozzle. Therefore, the pressure on workpiece increases, since assist gas flow from Laval nozzle can utilize energy more efficiently. However, caution is necessary in setting of cylinder gas pressure, since Laval nozzle has many unstable regions in which the pressure on workpiece changes periodically. Using Laval nozzle makes it possible to reduce the height of dross even under low cylinder gas pressure condition. Thus the consumption of assist gas flow quantity can be reduced. Moreover, it was pointed out that the convexed inner wall of nozzle leads of reduction of dross generation.

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  • A New Slicing Method of Monocrystalline Silicon Ingot by Wire EDM

    OKADA Akira, UNO Yoshiyuki, OKAMOTO Yasuhiro, ITOH Hisashi, HIRANO Tameyoshi

    International Journal of Electrical Machining   8   21 - 26   2003

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  • Precision Removal of ITO Film by LD‐pumped SHG YAG Laser.

    岡本康寛, 宇野義幸, 平尾泰之

    精密工学会誌   68 ( 12 )   1564 - 1569   2002.12

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  • Study on Laser Forming of Plastic by YAG Laser. Effect of Specimen Thickness on Deformation Characteristics.

    宇野義幸, 岡本康寛, 柴田隆義, 大久保雅史, 難波義治

    精密工学会誌   68 ( 3 )   466 - 471   2002.3

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    In this study, the effect of specimen thickness on machining characteristics and deformation mechanism of laser forming for plastic material with YAG laser were made clear by the experimental analysis. Each specimen with different thickness can be bent to 90 degrees under proper machining conditions. The optimum laser power, in which bending angle takes a maximum under the same feed condition, increases with an increase of specimen thickness. In the case of thick specimen, the deformation occurs without a delay between the beginning point and the end one of irradiation just after finishing of laser scan. On the other hand, thin specimen is deformed from the beginning point of irradiation during laser scan at a small number of laser scan, since the rigidity of thin specimen is lower compared to that of thick specimen. Consequently, the bending angle per one laser scan is small in the case of thin specimen. However, the bending angle per one laser scan becomes larger at a large number of laser scan. Because it is considered that the increase of rigidity of specimen leads to the stable deformation, since the hardness of irradiated area increases with an increase of laser irradiation.

    DOI: 10.2493/jjspe.68.466

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  • Micro machining of ITO film by LD pumped SHG YAG laser

    Yasuhiro Okamoto, Yoshiyuki Uno, Yasuyuki Hirao

    Proceedings of SPIE - The International Society for Optical Engineering   4830   40 - 45   2002

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    ITO film, which is a kind of transparent conductive film, has been used for LCD, PDF and so on. This film is mostly removed by wet etching method. However, this method needs many chemicals, numbers of process and large-size equipments. On the other hand, laser beam processing can achieve the dry process without chemicals and drastically reduces the number of process. Therefore, selective removal of ITO film on glass substrate by LD pumped Q-switch SHG YAG laser is experimentally investigated. Electric insulation across machined groove was successful. Better groove shape can be obtained by accurate control of defocused distance and feed rate under a constant average power. Using SHG YAG laser makes it possible to remove only ITO film without any damage to glass material as substrate, since SHG YAG laser of 532 nm in wavelength is easy to transmit the glass material. When laser beam is irradiated from ITO film to glass material, a non-removed portion of ITO film remains at the bottom of groove under long defocused distance condition. On the other hand, backside irradiation method, in which laser beam is irradiated to ITO film through glass material, can prevent from remaining a non-removed portion, since absorption of laser beam occurs from the boundary part between ITO film and glass material.

    DOI: 10.1117/12.486573

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  • Laser Cutting of Semiconductor Elements

    KOVALENKO Volodymyr S., UNO Yoshiyuki, ANYAKIN Mykola I., OKAMOTO Yasuhiro, SHABOUL Khaled-Al

    7   9 - 14   2002

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  • High performance slicing method of monocrystalline silicon ingot by wire EDM

    Y Uno, A Okada, Y Okamoto, T Hirano

    INITIATIVES OF PRECISION ENGINEERING AT THE BEGINNING OF A MILLENNIUM   219 - 223   2001

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    In this study, the slicing of silicon ingot by wire EDM is discussed, and the machining properties are experimentally investigated. Also, the accuracy of sliced wafer and the contamination on the machined surface are evaluated. Experimental results made it clear that the accuracy of wafer by this slicing method is almost the same as that by the conventional methods, and even higher slicing speeds are possible when multi type wire EDM slicing can be realized. Additionally, the contamination due to the adhesion and diffusion of wire electrode material into the sliced surface can be reduced by wire EDM under the condition of low current and long discharge duration. Therefore, wire EDM has a high potential as a new slicing method for monocrystalline silicon ingot.

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  • A New Micro EDM Technique of Monocrystalline Silicon using Fine Triangular Electrode

    Akira OKADA, Yoshiyuki UNO, Yasuhiro OKAMOTO, Hiroshi NAKASHIMA, Hidetou TANAKA, Sabrou OKADA

    Proceedings of the 13th International Symposium for Electromahining   2001

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  • Study on Precision Laser Forming of Plastic with YAG Laser.

    岡本康寛, 宇野義幸, 太田健一郎, 柴田隆義, 窪田真一郎, 難波義治

    精密工学会誌   66 ( 6 )   891 - 895   2000.6

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  • A New Slicing Method of Monocrystalline Silicon Ingot by Wire EDM.

    岡田晃, 宇野義幸, 岡本康寛, 伊藤久, 平野為義

    電気加工学会誌   34 ( 75 )   14 - 21   2000.3

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    DOI: 10.2526/jseme.34.14

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  • Effect of nozzle shape on surface integrity in micro cutting with pulsed YAG laser

    Y Okamoto, Y Uno, N Miyanagi

    1ST INTERNATIONAL SYMPOSIUM ON LASER PRECISION MICROFABRICATION   4088   291 - 294   2000

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    YAG laser has widely been used for precision micro machining in many fields. However, adhesions of dress and spatter to the base material due to high energy beam machining lead to the deterioration of the surface integrity. It is important to understand the assist gas flow from the tip of a convergent nozzle in order to improve the surface integrity, since material is mostly removed away by the gas flow spouted in the same direction of the laser beam.
    In this paper, effects of the nozzle shape on assist gas flow and the machined results were experimentally analyzed using the Schlieren method. There exists an unstable region in which the pressure on the workpiece changes periodically, and the region becomes wider with the reduction of the exit diameter. The pressure on the workpiece increases with an increase of the exit diameter, which makes the dress height smaller, However, it is necessary to select the nozzle shape according to the demand of the surface integrity, because the consumption of the assist gas increases and the kerf width becomes wider with an increase of the exit diameter. Moreover, it was pointed out that a kind of nozzle with a convex curve on inner wall of nozzle led to better surface integrity.

    DOI: 10.1117/12.405759

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  • Wire EDM slicing of monocrystalline silicon ingot

    Y Uno, A Okada, Y Okamoto, T Hirano

    PROCEEDINGS OF THE FIFTEENTH ANNUAL MEETING OF THE AMERICAN SOCIETY FOR PRECISION ENGINEERING   172 - 175   2000

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  • Precision laser forming of plastic with YAG laser Reviewed International journal

    Y Okamoto, Y Uno, T Shibata, K Ohta

    PROGRESS OF MACHINING TECHNOLOGY   221 - 226   2000

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    Laser forming of plastic materials with YAG laser is experimentally investigated. The bending angle increases rapidly in the cooling process just after laser irradiation and takes a maximum under a proper energy density. Slow feed rate and low power condition are recommended in order to obtain the better processing result, because the bending angle increases without reverse deformation at every laser irradiation scan and machined surface integrity under low power condition is better than that under high power one. Furthermore, in the case of plastics, the bending direction can be controlled by the selective painting of black resin on the top or bottom surface of specimen with only one-side laser irradiation, because heat is generated by absorbing laser beam energy into painted material. Therefore, various shapes can be obtained by varying both the laser scan and the painting part.

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  • Study on Supplying Method of Assist Gas in Precision Cutting with Pulsed YAG Laser. Reviewed

    宇野義幸, 岡本康寛, 広瀬和典, 川口茂孝, 窪田真一郎, 三柳直毅

    精密工学会誌   65 ( 10 )   1471 - 1475   1999.10

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    DOI: 10.2493/jjspe.65.1471

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  • High efficiency fine boring of monocrystalline silicon ingot by electrical discharge machining

    Y Uno, A Okada, Y Okamoto, K Yamazaki, SH Risbud, Y Yamada

    PRECISION ENGINEERING-JOURNAL OF THE AMERICAN SOCIETY FOR PRECISION ENGINEERING   23 ( 2 )   126 - 133   1999.4

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    This article deals with high efficiency and high accuracy fine boring in a monocrystalline silicon ingot by electrical discharge machining (EDM). In manufacturing process of integrated circuits, a plasma-etching process is used for removing oxidation films. This process has recently been examined for use of monocrystalline silicon as the electrode to minimize the contamination. However, it is difficult to machine silicon accurately by the conventional diamond drilling method, because the material removal is due to brittle fracture. The machining force in the EDM process is very small compared with that in conventional machining, therefore, the possibility of high efficiency and high accuracy boring holes in silicon ingot by EDM is experimentally investigated. The removal rate of monocrystalline silicon by EDM is much higher than that of steel, while the electrode wear is extremely small. The improvement method leads to a better hole without chipping at the exit of hole or sticking of the insulator on the wall of hole. Furthermore, it is proved that even a high aspect ratio of about 200 boring is possible. (C) 1999 Elsevier Science Inc. All rights reserved.

    DOI: 10.1016/S0141-6359(98)00029-4

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  • EDM Characteristics of CVD-Carbon Electrode Reviewed

    Yoshiyuki UNO, Akira OKADA, Hirohito NAKANISHI, Changning GUO, Yasuhiro OKAMOTO, Takashi TAKAGI

    International Journal of Electrical Machining   ( 3 )   19 - 24   1999

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  • A new slicing method of monocrystalline silicon ingot by wire EDM Reviewed

    A Okada, Y Uno, Y Okamoto

    12TH INTERNATIONAL SYMPOSIUM FOR ELECTROMACHINING (ISEM)   1405   417 - 424   1998

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    This paper deals with a new slicing method of monocrystalline silicon ingot by wire EDM. In manufacturing process of silicon wafer, ID blade and multi wire saw have conventionally been used for slicing of ingot. However, it is difficult to apply these methods for larger ingot such as 12(R) or 16 " expected to be used in the near future, since there are some problems in efficiency, accuracy, slurry treatment, contamination and so on. Therefore, a new slicing method is required as soon as possible. In this study, the possibility of slicing by WEDM was proposed and the machining properties as well as surface integrity were experimentally investigated. It was made clear that WEDM had the possibility as a new slicing method and that contamination due to adhesion and diffusion of wire electrode material to machined surface could be reduced by using the reversed polarity WEDM.

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  • A new micro EDM technique for fine complicated hole with triangular section electrode

    Y Uno, A Okada, Y Okamoto, K Watanabe, S Okada, Y Yamada

    PROCEEDINGS OF THE THIRTEENTH ANNUAL MEETING OF THE AMERICAN SOCIETY FOR PRECISION ENGINEERING   65 ( 1 )   239 - 242   1998

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    DOI: 10.2493/jjspe.65.155

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  • High Efficiency Penetration Boring of Single Crystalline Silicon Ingot by EDM.

    宇野義幸, 岡田晃, 岡本康寛

    精密工学会誌   63 ( 12 )   1725 - 1729   1997.12

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    In the manufacturing process of integrated circuit, graphite plate with many fine holes has been used as an electrode in plasma etching process. Recently, it is examined to use a single crystalline silicon as the electrode in order to minimize the contamination. However, it is difficult to machine accurately by the conventional methods, since the material removal is due to brittle fracture. The machining force in EDM is very small compared with that in conventional machining, therefore the possibility of high efficiency and high accuracy boring hole in a silicon ingot by EDM is experimentally investigated in this study. The removal rate of silicon is from 4 to 8 times higher than that of steel, while the electrode wear is from one-fifteenth to one-seventh times smaller. When the electrode advances at the exit of hole, stagnation region appears in which the electrode retracts suddenly and the machining becomes unstable. In order to prevent this phenomenon, the copper plate is closely attached under silicon ingot firmly. In this method, better hole can be obtained without chipping. Besides, there is no sticking of insulator which contains silicon oxide and copper oxide on the wall of hole in this case. Furthermore, it is proved that even high aspect ratio over 200 boring is possible.

    DOI: 10.2493/jjspe.63.1725

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  • Fundamental Study on Electrical Discharge Machining of Single Crystalline Silicon.

    宇野義幸, 岡田晃, 中西洋人, 岡本康寛

    精密工学会誌   63 ( 10 )   1459 - 1463   1997.10

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  • High efficiency fine boring of single crystalline silicon ingot by electrical discharge machining Reviewed

    Y Uno, A Okada, Y Okamoto, Y Yamada

    PROCEEDINGS OF THE TWELFTH ANNUAL MEETING OF THE AMERICAN SOCIETY FOR PRECISION ENGINEERING   525 - 528   1997

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  • EDM Characteristics of CVD‐Carbon Electrode. Reviewed

    宇野義幸, 岡田晃, 中西洋人, GUO C, 岡本康寛, 高木俊

    電気加工学会誌   30 ( 65 )   1 - 8   1996.11

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    In electrical discharge machining (EDM) process, the reduction of electrode wear is very important for high accuracy machining. It is reported that low electrode wear EDM can be achieved by the adhesions of workpiece material and heat resolved carbon from machining fluid to the electrode end surface, because of the protection effect of the latter which has large heat resistivity. Under a proper condition, even no electrode wear EDM is possible. Such adhesion phenomenon, however, is observed only on the condition that the pluse duration is relatively large. That is, it never occurs on the small pulse duration such as finishing condition. Therefore, no electrode wear EDM under finishing condition is impossible so far and the electrode wear in finishing EDM is practically allowed to be inevitable. It is reported that the heat resolved carbon from machining fluid adhering to the electrode end surface is turbostratic carbon. It has the chemical structure in which hexagonal lattice plane laminates irregularly, different from graphite structure. From these results, it is considered that no electrode wear EDM might be attained by using turbostratic carbon electrode under finishing condition.<br>In this study, EDM characteristics of a newly developed CVD-carbon electrode are experimentally investigated for higher performance EDM. Experimental analysis made it clear that low electrode wear EDM is possible by using CVD-carbon electrode even under finishing condition, since the heat resolved carbon from machining fluid has a stronger tendency to adhere to the end surface of CVD-carbon electrode than that of graphite one.

    DOI: 10.2526/jseme.30.65_1

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  • 先端半導体製造プロセスの最新動向と微細化技術

    技術情報協会( Role: Contributor ,  第1章 第2節 ワイヤ放電加工技術を用いた半導体材料のマルチスライシング法)

    (株)技術情報協会  2023.9  ( ISBN:9784861049828

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  • 精密加工と微細構造の形成技術

    技術情報協会  2013 

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  • 2013最先端ウェーハ&製造技術大全

    電子ジャーナル  2013 

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  • Nd YAG Laser "jointly worked"

    InTech  2012 

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  • アクチュエータが未来を創る(共著)

    岡山大学 アクチュエータ研究センター  2011 

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  • 太陽エネルギー有効利用最前線(共著)

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MISC

  • 2022年度光技術動向調査 光加工・計測

    岡本康寛

    2022年度光産業技術に関する報告書   2023.3

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  • 連続波レーザの斜角入射による金属の高速微細溝加工 Invited

    坂井辰彦, 田浦のぞみ, 岡本康寛, 岡田晃

    光アライアンス   33 ( 7 )   15 - 18   2022.7

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  • パルスレーザによる単結晶ダイヤモンドの高品位加工

    岡本康寛, 大久保翼, 岡田 晃

    電気加工技術(電気加工学会第235回研究会)   46 ( 143 )   22 - 27   2022.6

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    Authorship:Lead author, Last author, Corresponding author   Language:Japanese   Publishing type:Research paper, summary (national, other academic conference)  

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  • 2021年度光技術動向調査 光加工・計測 Invited

    岡本康寛

    2021年度光産業技術に関する報告書   2022.4

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  • レーザ加工の仕組みとアプリケーション Invited

    岡本康寛

    電気計算   90 ( 4 )   21 - 27   2022.3

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  • LPM2021ショート速報 Invited

    岡本康寛

    光産業技術振興協会国際会議速報   2021-No.06   2021.6

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  • 銅のレーザ溶接における光波長の効果 Invited Reviewed

    岡本康寛

    オプトニューズ   15 ( 6 )   2021.1

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  • LANE2020ショート速報 Invited

    岡本康寛

    光産業技術振興協会 国際会議速報   2020-No.06   2020.9

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  • 銅の微細レーザ溶接のおける光吸収特性と溶け込み深さの安定化に関する検討 Invited

    岡本 康寛

    FORM TECH REVIEW (天田金属加工機械技術振興財団編)   28   66 - 70   2019.3

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  • 高速レーザ走査を用いたステンレス箔の精密微細溶接の開発

    岡本康寛

    FORM TECH REVIEW (天田金属加工機械技術振興財団編)   27   68 - 72   2018

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  • グループ給電方式を用いた半導体材料のマルチワイヤ放電スライシング Invited

    岡本康寛, 岡田

    型技術 2017年3月増刊号 1冊でまるわかり! 放電加工技術の最前線2017   32 ( 4 )   18 - 21   2017

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  • ピコ秒パルスレーザを用いた透明体材料の内部加工 Invited

    岡本康寛, 岡田

    電気加工学会 学会創立50周年記念特集号   51 ( 126 )   152 - 157   2017

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  • Multi-slicing of Semiconductors by Wire Electrical Discharge Machining Technology Invited

    OKAMOTO Yasuhiro, OKADA Akira

    Journal of the Japan Society for Precision Engineering   83 ( 9 )   825 - 828   2017

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    DOI: 10.2493/jjspe.83.825

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  • 412 Effect of Pulse Duration on Material Removal of Iron by ns Pulsed Laser

    ITO Mizuna, SHINONAGA Togo, OKAMOTO Yasuhiro, OKADA Akira

    2016 ( 54 )   "412 - 1"-"412-2"   2016.2

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  • 409 Evaluation of Multi-wire EDM Slicing Characteristics with Group Power Supplying Method

    IKEDA Takayuki, OKAMOTO Yasuhiro, OKADA Akira, KURIHARA Haruya, KIDO Masataka

    2016 ( 54 )   "409 - 1"-"409-2"   2016.2

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  • 410 Effect of Laser Parameters on Ultrashort Pulsed Laser Induced Periodic Nanostructure Formed on Pure Titanium Plate

    KINOSHITA Shono, SHINONAGA Togo, OKAMOTO Yasuhiro, OKADA Akira

    2016 ( 54 )   "410 - 1"-"410-2"   2016.2

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  • Report on OPIC the Second Smart Laser Processing Conference (SLPC 2016)

    Yasuhiro OKAMOTO, Kunihiko WASHIO, Masahiro TSUKAMOTO

    レーザー研究   44 ( 9 )   622 - 623   2016

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  • LAMP2015ショート速報

    岡本康寛

    財団法人 光産業技術振興協会 国際会議速報   H27-No.07   2015

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  • Formation of Internal Modification with High Aspect Ratio in Sapphire by Sub-nanosecond Pulsed Fiber Laser Invited

    Yasuhiro OKAMOTO, Akira OKADA

    22 ( 2 )   20 - 25   2015

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  • High-quality Laser Micro-welding of Aluminum Alloy around Boundary Condition of Key-hole Generation Invited

    Yasuhiro OKAMOTO, Shin-ichi NAKASHIBA, Tomokazu SAKAGAWA, Akira OKADA

    22 ( 3 )   22 - 27   2015

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  • Micro-drilling of high hardness material by ns pulsed laser Invited

    58 ( 2 )   83 - 86   2014

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  • SLPC2014開催報告

    岡本康寛, 鷲尾邦彦, 塚本雅裕

    レーザ加工学会誌   21 ( 3 )   202 - 205   2014

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  • Report on ICALEO2013

    21 ( 2 )   92 - 98   2014

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  • 大面積電子ビーム照射による金型表面特性向上技術

    岡田 晃, 岡本康寛

    機械と工具   4 ( 4 )   317 - 23   2014

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  • LPM2014ショート速報

    岡本康寛

    財団法人 光産業技術振興協会 国際会議速報   H26-No.10   2014

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  • OPIC Conference on SLPC2014(スマートレーザプロセス会議2014)開催報告

    岡本康寛, 鷲尾邦彦, 塚本雅裕

    レーザー研究   42 ( 7 )   579 - 580   2014

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  • レーザー加工による多層化人工皮膚への皮膚蒸泄水分排出孔の形成に関する研究

    前田 直人, 潘 秋月, 岡本 康寛, 岡田 晃, 神 桂二, 坂本 隼一, 兒玉 直紀, 西川 悟郎, 皆木 省吾

    顎顔面補綴   36 ( 2 )   110 - 111   2013.12

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  • ICALEO2012参加報告

    大迫 康, 小市真樹, 萩野秀樹, 平野弘二, 宮本克彦, 山﨑洋輔, 岡本康寛

    レーザ加工学会誌   20 ( 2 )   32 - 45   2013

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  • パルスレーザによる微細溶接 Invited

    岡本康寛, 中芝伸一, 岡田 晃

    電気加工技術   37 ( 115 )   9 - 16   2013

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  • Analysis of Fluid Force Acting on Wire Electrode by Jet Flushing in Wire EDM

    KURIYAMA Kazuki, OKADA Akira, OKAMOTO Yasuhiro

    2012   31 - 34   2012.12

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  • Fundamental Study on Ceramics Film Formation by Large-area EB Irradiation

    MISUMI Shuhei, OKADA Akira, OKAMOTO Yasuhiro, INOUE Motohiro

    2012   65 - 68   2012.12

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  • Wide Operational Range Pulsed Fiber Laser for Micro Processing Invited

    19 ( 1 )   18 - 23   2012.3

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  • Pulse Duration Tunable Fiber Laser for Micro-Processing SumiLas

    Motoki Kakui, Shinobu Tamaoki, Yasuyoshi Kaneuchi, Hiroshi Koda, Yuji Tanaka, Yasuhiro Okamoto, Yoshiyuki Uno, Brian Baird

    ( 178 )   133 - 140   2012.1

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  • LPM2012ショート速報

    岡本康寛

    財団法人 光産業技術振興協会 国際会議速報   H24-No.8   2012

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  • Study on Surface Characteristics of EB Polished Cemented Carbide

    FUJITA Tomohiro, GUO Hongge, OKADA Akira, OKAMOTO Yasuhiro, UNO Yoshiyuki

    2011   27 - 30   2011.11

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  • Study on Releasability of Molded Resin from EDMed Surface with Powder Mixed Working Fluids

    ZHOU Zhiquan, OKAMOTO Yasuhiro, OKADA Akira, UNO Yoshiyuki, KITADA Ryoji

    2011   57 - 60   2011.11

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  • LPM2011ショート速報

    岡本康寛

    財団法人 光産業技術振興協会 国際会議速報   H23-No.10   2011

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  • Report on LPM2010

    Susumu Nakamura, Yasuhiro Okamoto

    Journal of Japan Laser Processing Society   18 ( 2 )   108 - 114   2011

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  • 大面積電子ビーム照射による金型の高能率表面仕上げ

    岡田 晃, 岡本康寛

    レーザ協会誌   36 ( 2 )   36 - 46   2011

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  • A33 Investigation of Micro-machining Characteristics and Phenomenon of Monocrystalline Silicon by Harmonics of Nd:YAG Laser

    Hirano Takayuki, Okamoto Yasuhiro, Uno Yoshiyuki, Sakagawa Tomokazu, Nkashiba Sin-ichi

    The ... Manufacturing & Machine Tool Conference   2010 ( 8 )   73 - 74   2010.11

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    Monocrystalline silicon has played an important role as semiconductors in the electronical and the electrical industries. High efficiency and high quality manufacturing process of silicon is required for the continuous development of these fields. However, debris and cracks remained on machined surface by the traditional mechanical processing because of its high brittleness. On the other hand, laser beam machining could realize the high-speed processing. However, heat affected zone and dross remained in the case of fundamental wavelength of Nd:YAG laser. In comparison, it is expected that harmonics of Nd:YAG laser make it possible to perform the high precision micro-machining with small heat affected zone and crack because of its high photon energy. In this study, the influence of wavelength and surrounding pressure was investigated with observing process behavior using a high-speed shutter camera in micro-machining of monocrystalline silicon by fundamental wavelength and harmonics of Nd:YAG laser.

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  • A24 Evaluation of Molten Zone in Micro-welding of Glass by Ultra-short Pulse Laser

    Yamamoto Keishi, Okamoto Yasuhiro, Uno Yoshiyuki, Cvecek Kristian, Schmid Michael

    The ... Manufacturing & Machine Tool Conference   2010 ( 8 )   59 - 60   2010.11

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    Fusion welding is well known as the most promising technique in glass joining, since joining can be accomplished without any intermediate layer and mechanical contact. High precision, small heat-affected zone (HAZ) and small shock-affected zone (SAZ) by ultra-short pulsed laser make it possible to perform the joining process with minimal damages to the surrounding area. However, there still remained a lot of things to be clarified in this process, since glass materials are very sensitive to temperature gradients. In this study, molten zones created by ultra-short pulsed laser in a fused silica glass were experimentally investigated. Laser irradiation was carried out inside the glass under various processing conditions. Molten zone was observed visually, and its mechanical strength was measured using three points bending test. The strength of molten zone was almost equal to the base material, and high strength could be obtained at low velocity and high pulse repetition rate condition.

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  • High-quality precision laser processing of next generation semiconductor substrate

    Yasuhiro Okamoto

    Annual Report of the Okayama Foundation for Science and Technology   ( 19 )   58 - 68   2010

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  • LPM2010ショート速報

    岡本康寛

    財団法人 光産業技術振興協会 国際会議速報   H22-No.9   2010

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  • ピコ秒レーザの海外動向

    岡本康寛

    光技術動向調査報告書   385 - 389   2009

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  • Multi-wire EDM Slicing Technology of Silicon Ingot Invited

    53 ( 11 )   663 - 666   2009

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  • LAMP2009ショート速報

    岡本康寛

    財団法人 光産業技術振興協会 国際会議速報   H21-No.14   2009

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  • D12 Fundamental Study on Micro-welding of Stainless Steel Foil by Fiber Laser

    Izawa Taito, Uno Yoshiyuki, Okamoto Yasuhiro

    The ... Manufacturing & Machine Tool Conference   2008 ( 7 )   135 - 136   2008.11

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    Recently, since the size of component becomes smaller, then the welding of thin metal foil has been required. Besides, the flexibility of process is important according to the accessibility especially for small components. The combination of micro-beam and high-speed laser scanning has the advantages for. metal foil welding. Therefore, the characteristics of micro-welding for stainless steel foil were investigated by high-speed laser scanning, in which the welding was carried out by high-speed scanner system with single-mode fiber laser. Assist gas is effective to generate smooth fusion bead even under high-speed scanning condition. Bead width and bead depth increased with increasing the scanning speed under the same energy density conditions, and high-energy efficiency was expected under high-speed laser scanning condition. The combination of smaller spot and high-speed laser scanning made it possible to obtain good overlap welding even in the case of 20 μm stainless foil.

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  • D13 Investigation of Internal Stress and Bending Characteristics in Laser Forming of Plastics

    Tanaka Shunsuke, Uno Yoshiyuki, Okamoto Yasuhiro, Nanba Yoshiharu, Mohid Zazuli

    The ... Manufacturing & Machine Tool Conference   2008 ( 7 )   137 - 138   2008.11

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    It is important to understand the characteristics of plastic material for applying the laser forming method to plastic material, since plastic material is very sensitive to temperature change. Plastic material is divided into two kinds of crystalline and non-crystalline, and deformation behavior would be different due to the difference of properties between crystalline and non-crystalline. Therefore, internal stress and deformation characteristics were experimentally investigated in laser forming of HDPE with crystal and ABS without crystal. Under the same maximum surface temperature condition, the bending angle of ABS was smaller than that of HDPE. Stress distributions were analyzed by FEM using results of unsteady heat condition analysis. Maximum equivalent stress of ABS was smaller than that of HDPE, and stress generation area of ABS was narrower due to the difference of thermophysical characteristics.

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  • D11 Fundamental Investigation into High Quality Laser Dicing Method for Solid Type Molded Composite Material

    Kitada Ryoji, Uno Yoshiyuki, Okamoto Yasuhiro, Doi Hiroyuki, Haraguchi Shin

    The ... Manufacturing & Machine Tool Conference   2008 ( 7 )   133 - 134   2008.11

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    Laser cutting has been expected as a new dicing method of semiconductor package, since the laser beam processing can control the cut shape easily with a narrow kerf. However, since the distance between cutting edge and silicon chip becomes narrow according to the size reduction of semiconductor package, the laser dicing with low heat affected zone is required. In this study, laser cutting characteristics of solid type molded composite material with the cooled gas were experimentally investigated. The cooled gas flow from the side of a coaxial assist gas for laser beam led to straighter kerf shape and cut surface with low heat affected zone. The combination of coaxial assist gas and side cooled gas made it possible to obtain constant and narrow kerf width for various feed rates. Moreover, the difference of kerf width between irradiation side and exit side became smaller by supplying the side cooled gas.

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  • 1004 Investigation of Surface Treatment Method by High-speed Scanning of Single-mode Fiber Laser with MOPA

    Mohri Tetsuomi, Uno Yoshiyuki, Okamoto Yasuhiro

    2008 ( 46 )   371 - 372   2008.2

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  • Development of High-performance Nozzle for High-precision Fine Laser Cutting Invited

    52 ( 10 )   573 - 576   2008

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  • 高性能ノズルを用いたシングルモードQスイッチファイバレーザによる薄板の精密切断加工

    岡本康寛

    (財)三豊科学技術協会研究成果報告書-平成17年度助成対象-   2008

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  • 高性能ノズルを用いたシングルモードファイバーレーザによる精密切断加工

    岡本康寛

    Annual Report of the Okayama Foundation for Science and Technology   66 - 74   2007

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  • フラウンホーファー・レーザ技術研究所(アーヘン工科大学)の滞在を通じて

    岡本康寛

    岡山大学工学部創造工学センターものづくり支援部門年報   ( 27号 )   12 - 13   2007

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  • ICALEO2006参加報告

    川人洋介, 塚本雅裕, 岡本康寛

    レーザ加工学会誌   14(2), 106-112   2007

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  • ラバルスロートノズルを利用したシングルモードファイバレーザによる薄板の精密切断加工

    岡本康寛

    (財)御器谷科学技術財団助成研究・国際交流活動報告集   15, 15-18   2007

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  • 5-102 Manufacturing Practice to Motivate a Sense of "Monotsukuri"

    UNO Yoshiyuki, OKADA Akira, OKAMOTO Yasuhiro

    18   84 - 85   2006.7

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  • 高品位精密レーザ切断加工用ノズルの開発

    岡本康寛, 宇野義幸, 櫻井茂行, 田原大和

    電気加工技術   30(95), 14-19   2006

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  • Nd:YAGレーザの高調波による窒化アルミニウムの微細穴加工

    岡本 康寛, 宇野 義幸, 谷野 至, 片岡 範生

    電気加工学会全国大会講演論文集   2005   9 - 10   2005.11

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  • ICALEO2004参加報告‐レーザ微細加工会議‐

    塚本雅裕, 岡本康寛, 比田井洋史

    レーザ加工学会誌   11 ( 3 )   175 - 181   2004.12

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  • Characteristics of Micro Drilling for Aluminum Nitride by Harmonics of Nd:YAG Laser

    OKAMOTO Yasuhiro, UNO Yoshiyuki, NAKASHIBA Shin-ichi, TANINO Itaru, KATAOKA Norio

    The ... Manufacturing & Machine Tool Conference   2004 ( 5 )   181 - 182   2004.11

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    Influence of wavelength and the kind of assist gas on machining characteristics of aluminum nitride using Q-switched Nd:YAG harmonics were experimentally investigated. Removal rate increases with the reduction of wavelength. Drilled depth increases proportionally with the number of laser shot at the beginning region of machining, while it stagnates after the proportional region. Drilled depth was greatly different by the kind of assist gas in the case of fundamental wavelength, while it was not influenced sensitively by the kind of assist gas in the case of harmonics because of its high photon energy. Debris was deposited remarkably except for fundamental wavelength, when blind hole is drilled using helium as the assist gas.

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  • ワイヤ放電技術を用いた単結晶シリコンのマルチスライシングに関する研究 : 安定な高速加工を目指した加工条件の検討

    鈴木 勝智, 宇野 義幸, 岡田 晃, 岡本 康寛, 平野 爲義

    電気加工学会全国大会講演論文集   2004   109 - 110   2004.11

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  • YAGレーザによる高密度ポリエチレンのレーザフォーミングに関する研究 : 変形特性の検討

    竹中 友彦, 宇野 義幸, 岡本 康寛, 難波 義治

    電気加工学会全国大会講演論文集   2004   61 - 64   2004.11

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  • プラスチックのレーザフォーミング

    岡本康寛

    FORM TECH REVIEW 2003(天田金属加工機械技術振興財団編)   13(1)32-37   2004

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  • YAGレーザ精密切断加工用ノズルの開発=アシストガス流の解析とノズル形状の効果=

    岡本康寛, 宇野義幸

    光アライアンス   15(5)23-30 ( 5 )   23 - 30   2004

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  • プラスチックのレーザフォーミング

    岡本康寛, 宮本 勇, 宇野義幸, 難波義治

    レーザ加工学会誌   10(3)11-16 ( 3 )   243 - 248   2003

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  • Precision Cutting of Thin Plate by Pulsed YAG Laser Using Laval Nozzle

    OKAMOTO Yasuhiro, UNO Yoshiyuki, HOSOGAYA Masayoshi, MIYANAGI Naoki

    The ... Manufacturing & Machine Tool Conference   2002 ( 4 )   159 - 160   2002.11

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    Effects of Laval nozzle on assist gas flow and the machined results in precision cutting of thin plate by pulsed YAG laser were experimentally investigated. Assist gas flow from Laval nozzle does not have Mach Shock Disk, and goes more straight than a traditional convergent nozzle. Therefore, the pressure on workpeice increases, since assist gas flow from Laval nozzle can utilize energy more efficiency. However, the caution is necessary in setting of cylinder gas pressure, since Laval nozzle has many unstable regions in which the pressure on workpiece changes periodically. Using Laval nozzle makes it possible to reduce the height of dross even under low cylinder gas pressure condition. Thus the consumption of flow quantity can be reduced. Moreover, it was pointed out that a convex curve on inner wall of nozzle leads to reduction of dross generation

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  • YAGレーザによる薄板の精密切断加工に及ぼすノズル形状の影響

    村上 義文, 宇野 義幸, 岡本 康寛, 三柳 直毅

    精密工学会大会学術講演会講演論文集   2001 ( 2 )   144 - 144   2001.9

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  • LD励起YAG第2高調波による透明体電極の精密加工

    平尾 泰之, 宇野 義幸, 岡本 康寛

    精密工学会大会学術講演会講演論文集   2001 ( 2 )   148 - 148   2001.9

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  • プラスチックのレーザフォーミングに関する研究 : 試料厚さが変形特性に及ぼす影響

    岡本 康寛, 宇野 義幸, 大久保 雅史, 柴田 隆義, 難波 義治

    精密工学会大会学術講演会講演論文集   2001 ( 2 )   165 - 165   2001.9

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  • LD励起QスイッチYAGレーザによる超微粒超硬合金の微細穴加工

    湯浅 英司, 宇野 義幸, 岡本 康寛

    精密工学会大会学術講演会講演論文集   2001 ( 2 )   147 - 147   2001.9

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  • Laser Welding of Slices of Magnetic Circuit

    S.kovalenko Volodymyr, Uno Yoshiyuki, Okamoto Yasuhiro, Anyakin M., Lutay A., Shubul Khaled Al.

    Memoirs of the Faculty of Engineering, Okayama University   35 ( 1 )   21 - 28   2001

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  • 放電を利用したシリコンインゴットのスライシング法

    伊藤 久, 宇野 義幸, 岡田 晃, 岡本 康寛, 平野 為義

    精密工学会大会学術講演会講演論文集   2000 ( 2 )   325 - 325   2000.9

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  • YAGレーザ加工におけるアシストガスの供給法に関する研究

    岡本 康寛, 宇野 義幸, 川口 茂孝, 窪田 真一郎, 廣瀬 和典, 三柳 直毅

    精密工学会大会学術講演会講演論文集   1998 ( 2 )   124 - 124   1998.9

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  • 単結晶シリコンの放電加工 Invited

    宇野義幸, 岡田晃, 岡本康寛

    精密工学会誌   64 ( 12 )   1739 - 1742   1998

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    Language:Japanese   Publishing type:Article, review, commentary, editorial, etc. (scientific journal)  

    DOI: 10.2493/jjspe.64.1739

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  • シリコンインゴットの放電スライシング法の提案

    宇野 義幸, 岡田 晃, 岡本 康寛, 郭 常寧

    精密工学会大会学術講演会講演論文集   1997 ( 1 )   723 - 724   1997.3

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  • 単結晶シリコンインゴット貫通放電穴加工に関する研究

    宇野 義幸, 岡田 晃, 岡本 康寛, 郭 常寧

    電気加工学会全国大会講演論文集   1996   91 - 94   1996.11

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Presentations

  • Investigation on Welding Phenomenon for Aluminum Alloy by Superposition of Pulsed YAG Laser and Diode Laser "jointly worked"

    Shin HARAGUCHI, Yasuhiro OKAMOTO, Yoshiyuki UNO, Tomokazu SAKAGAWA, Shin-ichi NAKASHIBA

    Proceedings of International Conference on Leading Edge Manufacturing in 21st Century  2009 

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    Event date: 2009

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  • Observation of Plasma Behavior in Micro-machining of Ceramics by Harmonics of Nd:YAG laser "jointly worked"

    Norihiro HAYASHI, Yasuhiro OKAMOTO, Yoshiyuki UNO, Tomokazu SKAGAWA

    Proceedings of International Conference on Leading Edge Manufacturing in 21st Century  2009 

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    Event date: 2009

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  • Micro-structuring Characteristics on Metal Surface by High-speed Scanning of Angled CW Laser Irradiation International conference

    Taiki Kawai, Riku Saitou, Atsuhiko Sakai, Yasuhiro Okamoto, Togo Shinonaga, Akira Okada

    25th International Symposium on Laser Precision Microfabrication – LPM2024  2024.6.14 

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    Event date: 2024.6.11 - 2024.6.14

    Language:English   Presentation type:Oral presentation (general)  

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  • History of LPM Invited International conference

    Yasuhiro Okamoto

    25th International Symposium on Laser Precision Microfabrication – LPM2024  2024.6.11 

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    Event date: 2024.6.11 - 2024.6.14

    Language:English   Presentation type:Symposium, workshop panel (nominated)  

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  • 振動攪拌を用いた粒子状石灰石のレーザ焼成に関する基礎的研究

    古武直樹, 岡本康寛, 岡田 晃, 静俊二郎, 藤木修治, 岡 正和

    日本機械学会中国四国支部第62期講演会  2024.3.8 

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    Event date: 2024.3.8

    Language:Japanese   Presentation type:Oral presentation (general)  

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  • レーザピーニングのオーバーラップ率が圧縮残留応力と疲労強度に及ぼす影響

    兵後翔太, 崎野良比呂, 加藤智治, 岡本康寛, 潘豪

    2023年度建築学会中国支部研究発表会  2024.3.2 

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    Event date: 2024.3.2

    Language:Japanese   Presentation type:Oral presentation (general)  

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  • レーザー切断・溶接の高効率・高品位化に関する取り組み Invited

    岡本康寛

    レーザー学会学術講演会第44回年次大会  2024.1.17  レーザー学会

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    Event date: 2024.1.16 - 2024.1.18

    Language:Japanese   Presentation type:Symposium, workshop panel (nominated)  

    Venue:東京  

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  • 硬脆材料のマルチワイヤ放電スライシングにおける加工溝幅均一性向上に関する検討

    吉田 匠, 越中脩太, 岡本康寛, 岡田晃, 栗原治弥

    2023年度精密工学会中国四国支部・九州支部共催 - 広島地方講演会 -  2023.12.9  公益社団法人 精密工学会

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    Event date: 2023.12.9

    Language:Japanese   Presentation type:Oral presentation (general)  

    Venue:東広島  

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  • 炭酸ガスレーザによる熱可塑性炭素繊維強化プラスチック板のレーザフォーミング特性の基礎評価 ― ピーク出力とパルス幅がレーザフォーミング特性に及ぼす影響 ―

    木崎晟那, 北田良二, 岡本康寛, 岡田晃

    2023年度精密工学会秋季大会学術講演会  2023.9.14  公益社団法人 精密工学会

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    Event date: 2023.9.13 - 2023.9.15

    Language:Japanese   Presentation type:Oral presentation (general)  

    Venue:博多  

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  • レーザピーニングにおける疲労強度向上効果に関する研究

    潘豪, 岡本康寛, 岡田晃, 梅津皓平, 崎野良比呂, 加藤智治

    2023年度精密工学会秋季大会学術講演会  2023.9.14  公益社団法人 精密工学会

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    Event date: 2023.9.13 - 2023.9.15

    Language:Japanese   Presentation type:Oral presentation (general)  

    Venue:博多  

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  • レーザ加工の基礎とアプリケーション Invited

    岡本康寛

    福岡県工業技術センター 令和5年度「第1回レーザ技術活用セミナー」  2023.7.11  福岡県工業技術センター

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    Event date: 2023.7.11

    Language:Japanese   Presentation type:Public lecture, seminar, tutorial, course, or other speech  

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  • Investigation on high-quality laser welding of copper and aluminum Invited International conference

    Yasuhiro Okamoto, Yuki Yamada, Akihiro Ochi, Akira Okada, Takeshi Yamamura, Katsutoshi Nagasaki, Kazunobu Mameno, Norio Nishi

    International Conference on Processing & Manufacuturing of Advanced Materials (THERMEC2023)  2023.7.4 

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    Event date: 2023.7.2 - 2023.7.7

    Language:English   Presentation type:Oral presentation (invited, special)  

    Venue:Wein  

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  • Micro-welding of Glass by Multiple Spot of Picosecond Pulsed Laser with Spatial Light Modulator International conference

    Ryo Takashima, Yasuhiro Okamoto, Akira Okada

    24th International Symposium on Laser Precision Microfabrication – LPM2023  2023.6.14 

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    Event date: 2023.6.13 - 2023.6.16

    Language:English   Presentation type:Oral presentation (general)  

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  • Fundamental Study on High-quality Micro-shape Fabrication on Monocrystalline Diamond by Nanosecond Pulsed Laser International conference

    Kaichi Kawata, Yasuhiro Okamoto, Akira Okada

    24th International Symposium on Laser Precision Microfabrication – LPM2023  2023.6.14 

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    Event date: 2023.6.13 - 2023.6.16

    Language:English   Presentation type:Oral presentation (general)  

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  • 光加工・計測応用の最新動向 Invited

    岡本康寛

    2023年度光技術動向セミナー  2023.4.20  光産業技術振興協会

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    Event date: 2023.4.20

    Language:Japanese   Presentation type:Public lecture, seminar, tutorial, course, or other speech  

    Venue:パシフィコ横浜  

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  • レーザー微細加工の基礎と動向 Invited

    岡本康寛

    OPIE'23レーザー基礎&応用技術セミナー  2023.4.20 

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    Event date: 2023.4.19 - 2023.4.21

    Language:Japanese   Presentation type:Public lecture, seminar, tutorial, course, or other speech  

    Venue:パシフィコ横浜  

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  • Recent topics of laser applications in Japan and high-quality Cu/Al laser welding Invited International conference

    Yasuhiro Okamoto

    8th Industrial Laser Applications Symposium, ILAS 2023  2023.3.22  AILU

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    Event date: 2023.3.22 - 2023.3.23

    Language:English   Presentation type:Oral presentation (keynote)  

    Venue:Daventry, UK  

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  • フレキシブル透明導電膜の低視認性高品位レーザ加工 Invited

    岡本康寛

    第8回バイオミメティクス加工技術研究会  2023.3.6  バイオミメティクス加工技術研究会

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    Event date: 2023.3.6

    Language:Japanese   Presentation type:Public lecture, seminar, tutorial, course, or other speech  

    Venue:長野  

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  • ツインスポットビームを用いた鉄鋼材料のファイバレーザ切断 Invited

    岡本康寛

    日本溶接協会 ガス溶断部会 技術委員会 2022年度第3回 溶断小委員会  2023.1.31  日本溶接協会

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    Event date: 2023.1.31

    Language:Japanese   Presentation type:Oral presentation (invited, special)  

    Venue:東京  

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  • 青色/近赤外レーザ斜角重畳照射による銅とアルミニウムの高品位溶接に関する基礎的研究

    山田雄基, 越智彬裕, 岡本康寛, 岡田晃, 西則男, 山村健, 長崎克俊, 豆野和延

    第 29回「エレクトロニクスにおけるマイクロ接合・実装技術」シンポジウム  2023.1 

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    Event date: 2023.1.24 - 2023.1.25

    Language:Japanese   Presentation type:Oral presentation (general)  

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  • 高繰り返しピコ秒パルスレーザーによるガラスとシリコンの微細溶融溶接 Invited

    岡本康寛, 岡田晃

    一般社団法人レーザー学会学術講演会第43回年次大会  2023.1.18  レーザー学会

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    Event date: 2023.1.18 - 2023.1.20

    Language:Japanese   Presentation type:Oral presentation (invited, special)  

    Venue:名古屋  

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  • 岡山大学特殊加工学研究室におけるレーザ加工

    岡本康寛

    第98回レーザ加工学会 講演会  2023.1.12  レーザ加工学会

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    Event date: 2023.1.11 - 2023.1.12

    Language:Japanese   Presentation type:Oral presentation (invited, special)  

    Venue:岡山  

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  • 斜角レーザ光照射における溶融金属の流動挙動解析 Invited

    岡本康寛

    FLOW-3D Japan Users Conference 2022  2022.11.17 

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    Event date: 2022.11.17 - 2022.11.18

    Language:Japanese   Presentation type:Public lecture, seminar, tutorial, course, or other speech  

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  • Fiber laser cutting of steel materials with twin spot beam-twin spot setting in kerf width direction International conference

    Kota Morimoto, Atsushi Yagi, Naoto Kai, Yasuhiro Okamoto, Akira Okada, Hiroaki Ishiguro, Ryohei Ito, Akihiko Sugiyama, Hiroshi Okawa

    41th International Congress on Applications of Lasers & Electro-Optics 2022  2022.10.18  Laser Institute of America

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    Event date: 2022.10.17 - 2022.10.19

    Language:English   Presentation type:Oral presentation (general)  

    Venue:Orland  

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  • 空間光位相変調器を用いたピコ秒パルスレーザ照射によるガラスの微細溶接

    高嶋 諒, 庵谷和希, 岡本康寛, 岡田 晃

    日本機械学会第14回 生産加工・工作機械部門講演会  2022.10.8  日本機械学会

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    Event date: 2022.10.8 - 2022.10.9

    Language:Japanese   Presentation type:Oral presentation (general)  

    Venue:金沢  

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  • ナノ秒パルスレーザと酸洗浄を用いた単結晶ダイヤモンドの高品位微細形状創成に関する基礎的検討

    河田開智, 大久保, 岡本康寛, 岡田 晃

    日本機械学会第14回 生産加工・工作機械部門講演会  2022.10.8  日本機械学会

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    Event date: 2022.10.7 - 2022.10.8

    Language:Japanese   Presentation type:Oral presentation (general)  

    Venue:金沢  

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  • レーザフォーミングによる熱可塑性炭素繊維強化プラスチック板の曲げ加工の基礎的検討

    渡辺里奈, 木崎晟那, 北田良二, 岡本康寛, 岡田 晃

    日本機械学会第14回 生産加工・工作機械部門講演会  2022.10.8  一般社団法人日本機械学会

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    Event date: 2022.10.7 - 2022.10.8

    Language:Japanese   Presentation type:Oral presentation (general)  

    Venue:金沢  

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  • ピコ秒パルスレーザによるガラスの微細溶融溶接 Invited

    岡本康寛

    2022年度溶接学会秋季全国大会フォーラム  2022.9.9 

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    Event date: 2022.9.9

    Language:Japanese   Presentation type:Oral presentation (invited, special)  

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  • 銅とアルミニウムのレーザ溶接における照射方法に関する基礎的研究

    越智 彬裕, 岡本 康寛, 岡田 晃, 林 佳佑, 山村 健, 長崎 克俊, 豆野 和延, 西 則男

    2022年度溶接学会秋季全国大会  2022.9.9 

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    Event date: 2022.9.8 - 2022.9.10

    Language:Japanese   Presentation type:Oral presentation (general)  

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  • 走査方向配置ツインスポットビームを用いた高品位ファイバレーザ切断法に関する基礎的研究

    甲斐直人, 森本紘太, 岡本康寛, 岡田 晃, 石黒宏明, 伊藤亮平, 大河弘志

    2022年度溶接学会秋季全国大会  2022.9.9 

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    Event date: 2022.9.8 - 2022.9.10

    Language:Japanese   Presentation type:Oral presentation (general)  

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  • Study on Improving Application of Compressive Residual Stress in ns Pulsed Laser Peening of High-strength Steel

    Pan Hao, Kohei Umezu, Yasuhiro Okamoto, Yoshihiro Sakino, Akira Okada

    23rd International Symposium on Laser Precision Microfabrication – LPM2022  2022.6.8 

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    Event date: 2022.6.7 - 2022.6.10

    Language:English   Presentation type:Oral presentation (general)  

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  • Study on Molten Metal Behavior and Formation Mechanism of Micro-structure by High-Speed Scanning of Angled CW Laser Irradiation

    Tatsuhiko Sakai, Nozomi Taura, Riku Saito, Yasuhiro Okamoto, Akira Okada

    16th International Conference on Laser Ablation  2022.4.27 

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    Event date: 2022.4.24 - 2022.4.29

    Language:English   Presentation type:Oral presentation (general)  

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  • Study on Irradiation Method of Near-infrared Laser Beam in Welding of Copper International conference

    Akihiro Ochi, Yasuhiro Okamoto, Akira Okada, Takeshi Yamamura, Norio Nishi

    4th Smart Laser Processing Conference SLPC2022  2022.4.21  Japan Laser Processing Society

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    Event date: 2022.4.19 - 2022.4.21

    Language:English   Presentation type:Oral presentation (general)  

    Venue:Yokohama  

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  • 斜め照射CWレーザの高速走査による金属表面への微細溝形成に焦点位置が及ぼす影響

    齊藤 陸, 田浦のぞみ, 岡本康寛, 岡田 晃, 坂井辰彦

    2022年度精密工学会春季大会学術講演会  2022.3.17 

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    Event date: 2022.3.15 - 2022.3.17

    Language:Japanese   Presentation type:Oral presentation (general)  

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  • 熱流体解析によるEB ポリッシングメカニズムの解明

    太田翔也, 田島 響, 篠永東吾, 岡本康寛, 岡田 晃

    2022年度精密工学会春季大会学術講演会  2022.3.15 

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    Event date: 2022.3.15 - 2022.3.17

    Language:Japanese   Presentation type:Oral presentation (general)  

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  • 空間位相変調器を用いたガラスの微細レーザ溶接に関する基礎的検討2022 Feburary

    庵谷 和希, 岡本 康寛, 岡田 晃

    第 28回「エレクトロニクスにおけるマイクロ接合・実装技術」シンポジウム  2022.2.3 

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    Event date: 2022.2.1 - 2022.2.14

    Language:Japanese   Presentation type:Oral presentation (general)  

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  • 放電加工の効率化とサーボ制御改善 Invited

    岡本康寛

    岡山県産業振興財団ミニシーズ発信会・交流会  2021.11.29  公益財団法人岡山県産業振興財団

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    Event date: 2021.11.29

    Language:Japanese   Presentation type:Public lecture, seminar, tutorial, course, or other speech  

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  • ツインスポットビームによる鉄鋼材料のレーザ切断 ―溝幅方向へのツインスポット配置―

    森本紘太, 甲斐直人, 岡本康寛, 岡田 晃, 石黒宏明, 伊藤亮平, 大河弘志, 杉山明彦, 藤田理央

    2021年度精密工学会中国四国支部・九州支部共催岡山地方講演会  2021.11.27 

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    Event date: 2021.11.27

    Language:Japanese   Presentation type:Oral presentation (general)  

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  • 熱可塑性炭素繊維強化プラスチックのレーザフォーミングにおけるレーザ光走査条件の実験的検討

    渡辺里奈, 北田良二, 川添孝志, 岡本 康寛, 岡田 晃

    2021年度精密工学会春秋大会学術講演会  2021.9.21 

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    Event date: 2021.9.21 - 2021.9.23

    Language:Japanese   Presentation type:Oral presentation (general)  

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  • レーザピーニングにおける圧縮残留応力付与効果向上に関する研究

    梅津皓平, 岡本康寛, 岡田晃, 崎野良比呂, 加藤智治, 王虹翕

    2021年度精密工学会春秋大会学術講演会  2021.9.21 

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    Event date: 2021.9.21 - 2021.9.23

    Language:Japanese   Presentation type:Oral presentation (general)  

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  • 超短パルスレーザによるガラスのマイクロ接合 Invited

    岡本康寛

    日本機械学会年次大会2021 先端技術フォーラム  2021.9.8 

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    Event date: 2021.9.8

    Language:Japanese   Presentation type:Oral presentation (invited, special)  

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  • CWレーザの斜角入射による金属の高速溝加工 Invited

    坂井辰彦, 田浦のぞみ, 岡本康寛, 岡田晃

    第95回レーザ加工学会講演会  2021.8.31 

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    Event date: 2021.8.30 - 2021.8.31

    Language:Japanese   Presentation type:Oral presentation (invited, special)  

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  • Fundamental Study on High-quality Micro-shape Fabrication of Monocrystalline Diamond by Nanosecond Pulsed Laser

    Tsubasa Okubo, Yasuhuro Okamoto, Akira Okada

    22nd International Symposium on Laser Precision Microfabrication (LPM2021)  2021.6.8 

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    Event date: 2021.6.8 - 2021.6.11

    Language:English   Presentation type:Oral presentation (general)  

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  • ファイバレーザ切断における光強度分布適正化を用いたドロス高さ低減法に関する基礎的検討

    甲斐直人, 門永星護, 岡本康寛, 岡田 晃, 杉山明彦, 石黒宏明, 伊藤亮平, 藤田理央, 大河弘志

    2021年度精密工学会春季大会学術講演会  2021.3.16 

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    Event date: 2021.3.16 - 2021.3.18

    Language:Japanese   Presentation type:Oral presentation (general)  

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  • CWレーザの斜め照射と高速走査による金属表面への微細溝形成とそのメカニズムに関する検討

    田浦のぞみ, 光延晃也, 岡本康寛, 岡田晃, 坂井辰彦

    2021年度精密工学会春季大会学術講演会  2021.3.16 

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    Event date: 2021.3.16 - 2021.3.18

    Language:Japanese   Presentation type:Oral presentation (general)  

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  • 炭酸ガスレーザを用いた熱可塑性炭素繊維強化プラスチックのフォーミング形状の基礎的検討

    北田 良二, 園田 涼平, 園田 湧真, 岡本 康寛, 岡田 晃

    2021年度精密工学会春季大会学術講演会  2021.3.16 

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    Event date: 2021.3.16 - 2021.3.18

    Language:Japanese   Presentation type:Oral presentation (general)  

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  • マルチワイヤ放電スライシングにおいてワイヤ走行により形成される加工液流れの基礎的検討

    田淵 愁笙, 竹川 智也, 岡本 康寛, 岡田 晃, 栗原 治弥

    2021年度精密工学会春季大会学術講演会  2021.3.16 

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    Event date: 2021.3.16 - 2021.3.18

    Language:Japanese   Presentation type:Oral presentation (general)  

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  • 連続発振近赤外線レーザを用いたCaCO3の焼成法に関する基礎的研究

    宮島 嵩文, 川崎 将大, 岡本 康寛, 藤木 修治, 岡 正和, 岡田 晃

    日本機械学会中国四国支部第59期講演会  2021.3.5 

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    Event date: 2021.3.5

    Language:Japanese   Presentation type:Oral presentation (general)  

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  • Effect of Free-electron Density on Joining Characteristics in Micro-welding of Glass by Ultrashort Pulsed Laser

    Zhiyong OUYANG, Yasuhiro OKAMOTO, Takumi FUJIWARA, Akira OKADA

    27th Symposium on Microjoining and Assembly Technology in Electronics  2021.2.2 

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    Event date: 2021.2.2 - 2021.2.3

    Language:English   Presentation type:Oral presentation (general)  

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  • 熱可塑性炭素繊維強化プラスチックのレーザフォーミング法に関する基礎的検討

    北田良二,岡本康寛,岡田 晃

    2020年度精密工学会秋季大会学術講演会  2020.9  精密工学会

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    Event date: 2020.9.1 - 2020.9.7

    Language:Japanese   Presentation type:Oral presentation (general)  

    Venue:On-line  

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  • 超短パルスレーザを用いた表面テクスチャリングによる鉄鋼系金型の撥水性制御に関する基礎的研究

    村田健太朗,篠永東吾,岡本康寛,岡田 晃

    2020年度精密工学会秋季大会学術講演会  2020.9  精密工学会

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    Event date: 2020.9.1 - 2020.9.7

    Language:Japanese   Presentation type:Oral presentation (general)  

    Venue:On-line  

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  • Evaluation of Mechanical Strength at High Energy Conditions in Micro-joining of Glass by Picosecond Pulsed Laser International conference

    Zhiyong Ouyang, Takumi Fujiwara, Yasuhiro Okamoto, Akira Okada

    21st International Symposium on Laser Precision Microfabrication  2020.6  Japan Laser Processing Society

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    Event date: 2020.6.23 - 2020.6.26

    Language:English   Presentation type:Oral presentation (general)  

    Venue:On-line  

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  • ピコ秒パルスレーザを用いた間隙を有するガラス板同士の接合

    藤原拓海, 欧陽智勇, 岡本康寛, 岡田 晃

    2020年度精密工学会春季大会学術講演会  2020.3.17  精密工学会

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    Event date: 2020.3.17

    Language:Japanese   Presentation type:Oral presentation (general)  

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  • グループ給電方式マルチワイヤ放電スライシングにおける極間検出電圧変動域制御法の検討

    竹川智也,田淵愁笙,岡本康寛,岡田 晃,栗原治弥

    2020年度精密工学会春季大会学術講演会  2020.3.17  精密工学会

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    Event date: 2020.3.17

    Language:Japanese   Presentation type:Oral presentation (general)  

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  • マルチワイヤ放電スライシング

    岡本康寛,岡田 晃

    電気加工学会放電加工現象基礎研究委員会第7回研究委員会  2020.1.15  電気加工学会

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    Event date: 2020.1.15

    Language:Japanese   Presentation type:Oral presentation (invited, special)  

    Venue:福岡大学  

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  • マイクロ秒パルスレーザを用いた金型材料の微細領域表面粗低減法に関す基礎的検討

    梅津皓平,小崎拓朗,岡本康寛,岡田 晃

    2019年度 精密工学会九州支部・中国四国支部共催「佐世保地方講演会」  2019.12.14  精密工学会

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    Event date: 2019.12.14

    Language:Japanese   Presentation type:Oral presentation (general)  

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  • 液相上の固相金属に対するレーザ穴加工プロセスとその貫通検出法の検討

    田浦のぞみ, 川﨑千佳子, 岡本康寛, 岡田 晃, 坂井辰彦

    2019年度 精密工学会九州支部・中国四国支部共催「佐世保地方講演会」  2019.12.14  精密工学会

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    Event date: 2019.12.14

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  • ファイバレーザを用いた鉄鋼材料の窒素切断におけるドロス低減に関する基礎的研究

    矢木敦士,門永星護,岡本康寛,岡田 晃,石黒宏明,伊藤亮平,溝口祐也,杉山明彦,藤田理央

    2019年度 精密工学会九州支部・中国四国支部共催「佐世保地方講演会」  2019.12.14  精密工学会

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    Event date: 2019.12.14

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  • 炭酸ガスレーザを用いた炭素繊維強化プラスチックのレーザフォーミングに関する基礎的研究

    北田 良二,岡本 康寛,岡田 晃

    第13回 日本機械学会生産加工・工作機械部門講演会  2019.10.4  日本機械学会

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    Event date: 2019.10.4

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  • 近赤外レーザを用いた銅の微細溶接における開口数と表面粗さの影響

    川崎将大,濱田一樹,岡本康寛,岡田 晃,西 則男,酒川友一

    第13回 日本機械学会生産加工・工作機械部門講演会  2019.10.4  日本機械学会

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    Event date: 2019.10.4

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  • ナノ秒パルスファイバーレーザを用いた単結晶ダイヤモンドに対する高品位微細加工

    梶谷敦也,岡本康寛,岡田 晃

    2019年度精密工学会秋季大会学術講演会  2019.9.3  精密工学会

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    Event date: 2019.9.3

    Language:Japanese   Presentation type:Oral presentation (general)  

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  • Effect of Numerical Aperture on Molten Area Characteristics in Micro-joining of Glass by Picosecond Pulsed Laser International conference

    Yasuhiro Okamoto, Zhiyong Ouyang, Takuya Fujiwara, Akira Okada

    Commission VII: Microjoining and Nanojoining, the 72nd International Institute of Welding Annual Assembly and International Conference  2019.7.9  International Institute of Welding

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    Event date: 2019.7.9

    Language:English   Presentation type:Oral presentation (general)  

    Venue:ブラチスラバ  

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  • Study on Reduction of Slope Angle of Kerf in Thick Plate Cutting of Mild Steel by Fiber Laser International conference

    Seigo Kadonoga, Kyo Kitagawa, Yasuhiro Okamoto, Akira Okada, Hiroaki Ishiguro, Ryohei Ito, Akihiko Sugiyama, Hironobu Miyoshi, Ayako Nagase

    8th International Congress on Laser Advanced Materials Processing (LAMP2019)  2019.5  Japan Laser Processing Society

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    Event date: 2019.5.21 - 2019.5.24

    Language:English   Presentation type:Oral presentation (general)  

    Venue:広島国際会議場  

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  • High-quality Microfabrication of Monocrystalline Diamond by Picosecond Pulsed Laser International conference

    Atsuya Kajitani, Takahiro Simose, Yasuhiro Okamoto, Togo Sinonaga, Akira Okada

    8th International Congress on Laser Advanced Materials Processing (LAMP2019)  2019.5  Japan Laser Processing Society

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    Event date: 2019.5.21 - 2019.5.24

    Language:English   Presentation type:Oral presentation (general)  

    Venue:広島国際会議場  

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  • 銅の微細レーザ溶接のおける光吸収特性と溶け込み深さの安定化に関する検討

    岡本康寛

    平成30年度特別電源所在県科学技術振興事業研究成果発表会  2019.3.15  岡山県

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    Event date: 2019.3.15

    Language:Japanese   Presentation type:Poster presentation  

    Venue:岡山プラザルホテル  

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  • 初期表面粗さに起因するLIPSSの形状変化に及ぼすレーザ照射条件の影響

    和田祐樹,篠永東吾,岡本康寛,岡田 晃

    2019年度精密工学会春季大会学術講演会  2019.3.13  精密工学会

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    Event date: 2019.3.13

    Language:Japanese   Presentation type:Oral presentation (general)  

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  • 連続発振レーザの高速走査を用いた微細溝形成に関する基礎的検討

    片山千絵,北川 京,岡本康寛,岡田 晃

    日本機械学会中国四国支部第57期講演会  2019.3.7  日本機械学会中国四国支部

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    Event date: 2019.3.7

    Language:Japanese   Presentation type:Oral presentation (general)  

    Venue:山口大学  

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  • 溶接困難材料の高効率・高品位レーザ溶接 International conference

    岡本康寛,Martin Ruthandi Maina,濱田一樹,川崎将大,岡田 晃

    第18回国際工作機械技術者会議  2018.11  精密工学会

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    Event date: 2018.11.3 - 2018.11.4

    Language:Japanese   Presentation type:Oral presentation (general)  

    Venue:東京ビッグサイト  

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  • ファイバレーザを用いた軟鋼厚板切断における加工溝傾斜角低減に関する検討

    門永星護,北川 京,岡本康寛,岡田 晃,石黒宏明,伊藤亮平,杉山明彦,三吉弘信,長瀬絢子

    2018年度精密工学会中国四国支部香川地方学術講演会  2018.10.27  精密工学会

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    Event date: 2018.10.27

    Language:Japanese   Presentation type:Oral presentation (general)  

    Venue:高松  

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  • ピコ秒パルスレーザを用いた単結晶ダイヤモンドに対する高品位微細加工

    梶谷敦也,下瀬貴大,岡本康寛,篠永東吾,岡田 晃

    2018年度精密工学会中国四国支部香川地方学術講演会  2018.10.27  精密工学会

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    Event date: 2018.10.27

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    Venue:高松  

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  • 銅の微細レーザ溶接における表面性状と光吸収特性に関する研究

    川崎将大,濱田一樹,岡本康寛,岡田 晃,中芝伸一,酒川友一

    2018年度精密工学会中国四国支部香川地方学術講演会  2018.10.27  精密工学会

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    Event date: 2018.10.27

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    Venue:高松  

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  • 液相上の固相金属に対するレーザ穴加工プロセスとその貫通検出法

    川﨑千佳子, 岡本康寛, 岡田 晃, 今井浩文

    2018年度精密工学会中国四国支部香川地方学術講演会  2018.10.27  精密工学会

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    Event date: 2018.10.27

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    Venue:高松  

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  • グリーンマイクロ秒パルスレーザによる金型材料の表面粗さ低減に関する検討

    小崎拓朗,篠永東吾,岡本康寛,岡田 晃

    第12回 生産加工・工作機械部門講演会  2018.10.13  機械学会

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    Event date: 2018.10.13 - 2018.10.14

    Language:Japanese   Presentation type:Oral presentation (general)  

    Venue:兵庫県立大学  

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  • アルミニウム合金の高速レーザ溶接において強度分布がビード表粗さに及ぼす影響

    岡本 康寛,Maina Martin Ruthandi,岡田 晃, N?rhi Matti, Kangastupa Jarno,Vihinen Jorma

    2018年度精密工学会秋季大会学術講演会  2018.9.5  精密工学会

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    Event date: 2018.9.5

    Language:Japanese   Presentation type:Oral presentation (general)  

    Venue:函館アリーナ  

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  • Stabilization of Fusion Micro-welding of Glass by Picosecond Pulsed Laser International conference

    Yasuhiro Okamoto, Yuta Ogino, Togo Shinonaga, Akira Okada

    International Conference on Processing and Manufacturing of Advanced Materials (THERMEC '2018)  2018.7  International Conference on Processing and Manufacturing of Advanced Materials (THERMEC '2018)

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    Event date: 2018.7.8 - 2018.7.13

    Language:English   Presentation type:Oral presentation (invited, special)  

    Venue:パリ  

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  • Effects of Polarization on Removal Characteristics of Silver Nanowires in Transparent Conductive Film by fs Pulsed Laser International conference

    Yasuhiro Okamoto, Takahiro Shimose, Norio Nishi, Togo Shinonaga, AkiraOkada

    19th International Symposium on Laser Precision Microfabrication  2018.6  Japan Laser Processing Society

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    Event date: 2018.6.25 - 2018.6.28

    Language:English   Presentation type:Oral presentation (general)  

    Venue:エジンバラ  

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  • Basics and Advanced Applications of Laser Material Processing International conference

    2018.5 

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    Event date: 2018.5.4

    Language:English   Presentation type:Oral presentation (invited, special)  

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  • Investigation of Surface Quality in High Speed Laser Welding of Aluminum Alloy using Adjustable Ring-mode Fiber Laser International conference

    Martin Ruthandi Maina, Yasuhiro Okamoto, Akira Okada, Matti N?rhi, Jarno Kangastupa, Jorma Vihinen

    2018 Sustainable Research and Innovation Conference  2018.5  Jomo Kenyatta University of Agriculture and Technology

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    Event date: 2018.5.2 - 2018.5.3

    Language:English   Presentation type:Oral presentation (general)  

    Venue:Juja  

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  • Thought of Future Manufacturing (MONOZUKURI) -Laser Beam Processing- International conference

    Yasuhiro Okamoto

    2018 Sustainable Research and Innovation Conference  2018.5  Jomo Kenyatta University of Agriculture and Technology

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    Event date: 2018.5.2 - 2018.5.3

    Language:English   Presentation type:Oral presentation (invited, special)  

    Venue:Juja  

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  • Influence of Intensity Distribution on Surface Quality in High Speed Laser Welding of Aluminum Alloy International conference

    Martin Ruthandi Maina, Yasuhiro Okamoto, Akira Okada, Matti N?rhi, Jarno Kangastupa, Jorma Vihinen

    Third Smart Laser Processing Conference  2018.4  Japan Laser Processing Society

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    Event date: 2018.4.26

    Language:English   Presentation type:Poster presentation  

    Venue:横浜  

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  • ガラスのピコ秒パルスレーザ溶接において溶融領域がガラスの接合強度に及ぼす影響

    荻野雄太,欧?智勇,岡本康寛,篠永東吾,岡田 晃

    2018年度精密工学会春季大会学術講演会  2018.3.17  精密工学会

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    Event date: 2018.3.17

    Language:Japanese   Presentation type:Oral presentation (general)  

    Venue:中央大学  

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  • ファイバレーザを用いた軟鋼厚板切断における加工溝傾斜角の改善に関する基礎的研究

    北川 京,岡本康寛,篠永東吾,岡田 晃,石黒宏明,杉山明彦,三吉弘信,伊藤亮平

    2018年度精密工学会春季大会学術講演会  2018.3.17  精密工学会

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    Event date: 2018.3.17

    Language:Japanese   Presentation type:Oral presentation (general)  

    Venue:中央大学  

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  • 超短パルスによる非金属材料のレーザ接合

    岡本康寛,金谷雅仁,池田崇之,栗原治弥,岡田 晃,木戸正孝

    2018年度精密工学会春季大会学術講演会シンポジウム資料集(レーザおよびレーザ援用加工の新展開)  2018.3.16  精密工学会

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    Event date: 2018.3.16

    Language:Japanese   Presentation type:Oral presentation (invited, special)  

    Venue:中央大学  

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  • 高繰り返しピコ秒パルスレーザによるガラスと半導体材料のクラックレス直接接合法

    岡本康寛

    平成29年度特別電源所在県科学技術振興事業研究成果発表会  2018.3.16  岡山県

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    Event date: 2018.3.16

    Language:Japanese   Presentation type:Poster presentation  

    Venue:岡山プラザルホテル  

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  • チタンの初期表面粗さが超短パルスレーザ誘起ナノ周期構造の形状に及ぼす影響

    和田祐樹,木下奨之,篠永東吾,岡本康寛,岡田 晃

    日本機械学会中国四国支部第56期講演会  2018.3.7  日本機械学会中国四国支部

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    Event date: 2018.3.7

    Language:Japanese   Presentation type:Oral presentation (general)  

    Venue:徳島大学  

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  • パルスレーザを用いた銀ナノワイヤ透明導電膜に対する絶縁領域形成とその評価

    田中康貴,下瀬貴大,岡本康寛,篠永東吾,岡田 晃,西 則男

    2017年度精密工学会中国四国支部鳥取地方学術講演会  2017  精密工学会中国四国支部

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    Event date: 2017.11.25

    Language:Japanese   Presentation type:Oral presentation (general)  

    Venue:鳥取コンベンションセンター  

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  • 液相上の固相金属に対するレーザ穴加工とその貫通検出法に関する基礎的検討

    川﨑千佳子,伊藤瑞菜,岡本康寛,篠永東吾,岡田 晃,今井浩文

    2017年度精密工学会中国四国支部鳥取地方学術講演会  2017  精密工学会中国四国支部

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    Event date: 2017.11.25

    Language:Japanese   Presentation type:Oral presentation (general)  

    Venue:鳥取コンベンションセンター  

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  • つり下げ電極を用いた曲がり穴放電加工法における工作物振動の効果と小径穴加工の安定化

    太田浩平,李 碩?,岡本康寛,岡田 晃,山口 篤

    2017年度精密工学会中国四国支部鳥取地方学術講演会  2017  精密工学会中国四国支部

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    Event date: 2017.11.25

    Language:Japanese   Presentation type:Oral presentation (general)  

    Venue:鳥取コンベンションセンター  

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  • Nd:YAGレーザを用いた銅の微細溶接における光吸収特性 ?光吸収率と溶融量の評価?

    濱田一樹,井上礼輝,岡本康寛,篠永東吾,岡田 晃,中芝伸一,酒川友一

    2017年度精密工学会中国四国支部鳥取地方学術講演会  精密工学会中国四国支部

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    Event date: 2017.11.25

    Language:Japanese   Presentation type:Oral presentation (general)  

    Venue:鳥取コンベンションセンター  

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  • 細胞配向性向上のための超短パルスレーザによる表面形状制御に関する研究

    篠永東吾,木下奨之,和田祐樹,岡本康寛,岡田 晃

    2017年度精密工学会秋季大会学術講演会  2017  精密工学会

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    Event date: 2017.9.20 - 2017.9.22

    Language:Japanese   Presentation type:Oral presentation (general)  

    Venue:大阪大学  

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  • 超短パルスレーザを用いた銀ナノワイヤ透明導電膜の除去特性に偏光方向が及ぼす影響

    下瀬貴大,大下雅史,岡本康寛,西 則男,篠永東吾,岡田 晃

    2017年度精密工学会秋季大会学術講演会  2017  精密工学会

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    Event date: 2017.9.20 - 2017.9.22

    Language:Japanese   Presentation type:Oral presentation (general)  

    Venue:大阪大学  

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  • レーザ加工の高品位・高機能化

    岡本康寛

    (公財)岡山工学振興会 平成29年度研究助成金贈呈式  2017  (公財)岡山工学振興会

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    Event date: 2017.7.11

    Language:Japanese  

    Venue:岡山ロイヤルホテル  

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  • Fundamental Study on Slicing Method of Gallium Nitride by Ultrashort Pulsed Laser International conference

    Togo Shinonaga, Motoki Ota, Yasuhiro Okamoto, Akira Okada

    18th International Symposium on Laser Precision Microfabrication  2017  Japan Laser Processing Society

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    Event date: 2017.6.6 - 2017.6.9

    Language:English   Presentation type:Oral presentation (general)  

    Venue:富山  

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  • 純チタンの鉛直面リモートレーザ溶接における広範囲アルゴンガスシールド法

    北川 京,横原和男,篠永東吾,岡本康寛,岡田 晃,落合彦太郎,木村陵介,小野昇造,赤瀬雅之

    2017年度精密工学会春季大会学術講演会  2017  精密工学会

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    Event date: 2017.3.13 - 2017.3.15

    Language:Japanese   Presentation type:Oral presentation (general)  

    Venue:慶応大学  

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  • マルチワイヤ放電スライシング法における加工溝幅均一性の検討

    岡本康寛,金谷雅仁,池田崇之,栗原治弥,岡田 晃,木戸正孝

    2017年度精密工学会春季大会学術講演会  2017  精密工学会

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    Event date: 2017.3.13 - 2017.3.15

    Language:Japanese   Presentation type:Oral presentation (general)  

    Venue:慶応大学  

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  • スタート穴を用いたワイヤ放電加工開始時におけるノズルフラッシングがワイヤ断線に及ぼす影響

    川田晃嘉,岡本康寛,岡田 晃,栗原治弥

    2017年度精密工学会春季大会学術講演会  2017  精密工学会

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    Event date: 2017.3.13 - 2017.3.15

    Language:Japanese   Presentation type:Oral presentation (general)  

    Venue:慶応大学  

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  • 開口数がピコ秒レーザによるガラスの微細溶融溶接特性に及ぼす影響

    篠永東吾,太田元基,渡邉大祐,岡本康寛,岡田 晃

    2017年度精密工学会春季大会学術講演会  2017  精密工学会

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    Event date: 2017.3.13 - 2017.3.15

    Language:Japanese   Presentation type:Oral presentation (general)  

    Venue:慶応大学  

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  • グループ給電方式マルチワイヤ放電スライシング法における極間制御の高機能化

    岡本康寛

    平成28年度特別電源所在県科学技術振興事業研究成果発表会  2017  岡山県

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    Event date: 2017.3.10

    Language:Japanese   Presentation type:Poster presentation  

    Venue:岡山プラザルホテル  

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  • グループ給電方式を用いた円形断面材料のマルチワイヤ放電スライシング

    金谷雅仁,池田崇之,岡本康寛,岡田 晃,栗原治弥,木戸正孝

    日本機械学会中国四国支部第54期講演会  2017  日本機械学会

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    Event date: 2017.3.7

    Language:Japanese   Presentation type:Oral presentation (general)  

    Venue:広島工業大学  

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  • ナノ秒パルスレーザを用いた軟鋼材の加工においてパルス幅が材料到達エネルギーに及ぼす影響

    伊藤 瑞菜,篠永 東吾,岡本康寛,岡田 晃

    レーザー学会第37回年次大会講演論文集  2017  レーザー学会

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    Event date: 2017.1.7

    Language:Japanese   Presentation type:Oral presentation (general)  

    Venue:徳島大学  

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  • ワイヤ放電技術を用いた マルチスライシングへの取り組み

    岡本康寛,岡田 晃

    「結晶加工と評価技術」第145委員会 第151回研究会資料集  2016  (独)日本学術振興会

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    Event date: 2016.12.14

    Language:Japanese   Presentation type:Oral presentation (invited, special)  

    Venue:中央大学  

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  • ピコ秒パルスレーザによるガラスの微細溶融溶接の安定化

    岡本康寛,岡田 晃

    第86回レーザ加工学会論文集  2016  レーザ加工学会

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    Event date: 2016.12.12 - 2016.12.13

    Language:Japanese   Presentation type:Oral presentation (invited, special)  

    Venue:大阪大学  

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  • 純チタンの横向きリモートレーザ溶接における広範囲アルゴンガスシールド法

    横原和男,北川 京,篠永東吾,岡本康寛,岡田 晃,落合彦太郎,木村陵介,小野昇造,赤瀬雅之

    第86回レーザ加工学会論文集  2016  レーザ加工学会

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    Event date: 2016.12.12 - 2016.12.13

    Language:Japanese   Presentation type:Poster presentation  

    Venue:大阪大学  

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  • ガラスの微細レーザ溶接における開口数の影響

    太田元基,渡邉大祐,岡本康寛,篠永東吾,岡田 晃

    第86回レーザ加工学会論文集  2016  レーザ加工学会

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    Event date: 2016.12.12 - 2016.12.13

    Language:Japanese   Presentation type:Poster presentation  

    Venue:大阪大学  

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  • ナノ秒レーザによる銀ナノワイヤ透明導電膜の低視認性プロセスの検討

    大下雅史,西 則男,下瀬貴大,岡本康寛,篠永東吾,岡田 晃

    第86回レーザ加工学会論文集  2016  レーザ加工学会

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    Event date: 2016.12.12 - 2016.12.13

    Language:Japanese   Presentation type:Poster presentation  

    Venue:大阪大学  

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  • レーザ微細溶接の安定化への取り組み

    岡本康寛

    平成28年度多元技術融合光プロセス研究会第4回研究交流会資料集  2016  多元技術融合光プロセス研究会

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    Event date: 2016.12.6

    Language:Japanese   Presentation type:Oral presentation (invited, special)  

    Venue:岡山大学  

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  • SiCへのレーザ穴加工技術

    岡本康寛

    平成28年度 地域中核企業創出・支援事業「次世代グリーンデバイス関連産業創出事業」第1回 次世代パワーデバイス研究会  2016 

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    Event date: 2016.11.29

    Language:Japanese  

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  • ピコ秒パルスレーザを用いたガラスの微細溶融溶接における開口数の影響

    渡邉大祐,太田元基,岡本康寛,篠永東吾,岡田 晃

    2016年度精密工学会中国四国支部山口地方学術講演会  2016  精密工学会中国四国支部

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    Event date: 2016.11.26

    Language:Japanese   Presentation type:Oral presentation (general)  

    Venue:大船商専  

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  • ナノ秒パルスレーザを用いた銀ナノワイヤ透明導電膜の除去特性と不可視性評価

    下瀬貴大,大下雅史,西 則男,岡本康寛,篠永東吾,岡田 晃

    2016年度精密工学会中国四国支部山口地方学術講演会  2016  精密工学会中国四国支部

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    Event date: 2016.11.26

    Language:Japanese   Presentation type:Oral presentation (general)  

    Venue:大船商専  

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  • Molten Area Characteristics in Micro-welding of Glass by Picosecond Laser

    Imaduddin Helmi Bin Wan Nordin,Yasuhiro Okamoto,Akira Okada,Motoki Ota,Tomokazu Sakagawa

    第11回 生産加工・工作機械部門講演会  2016  日本機械学会

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    Event date: 2016.10.22 - 2016.10.23

    Language:English   Presentation type:Oral presentation (general)  

    Venue:名古屋  

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  • ナノ秒レーザを用いた軟鋼材の加工においてパルス幅が材料到達エネルギーに及ぼす影響

    伊藤瑞菜,篠永東吾,岡本康寛,岡田 晃

    第11回 生産加工・工作機械部門講演会  2016  日本機械学会

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    Event date: 2016.10.22 - 2016.10.23

    Language:Japanese   Presentation type:Oral presentation (general)  

    Venue:名古屋  

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  • レーザ加工の基礎とアプリケーション

    岡本康寛

    しまね金型研究会  2016  しまね金型研究会

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    Event date: 2016.9.30

    Language:Japanese   Presentation type:Oral presentation (invited, special)  

    Venue:松江市  

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  • ナノ秒パルスレーザによる銀ナノワイヤ透明導電膜の除去加工特性と視認性評価

    西 則男,大下雅史,下瀬貴大,岡本康寛,篠永東吾,岡田 晃

    2016年度精密工学会秋季大会学術講演会  2016  精密工学会

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    Event date: 2016.9.6 - 2016.9.8

    Language:Japanese   Presentation type:Oral presentation (general)  

    Venue:茨木大学  

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  • SiおよびSiCのマルチワイヤ放電スライシング法の開発

    岡本 康寛,岡田 晃

    2016年度精密工学会秋季大会学術講演会シンポジウム(次世代非球面金型やパワー半導体基板を目指す炭化ケイ素の超精密加工)  2016  精密工学会

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    Event date: 2016.9.6

    Language:Japanese   Presentation type:Symposium, workshop panel (nominated)  

    Venue:茨木大学  

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  • 高エネルギービーム加工の高機能化 -レーザ・放電加工への取り組み-

    岡本康寛

    津山高専技術交流プラザ・津山商工会議所合同産学連携交流会 

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    Event date: 2016.7.28

    Language:Japanese   Presentation type:Oral presentation (invited, special)  

    Venue:津山国際ホテル  

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  • 超短パルスレーザ誘起ナノ周期構造の形状制御に関する検討

    木下 奨之,篠永 東吾,岡本 康寛,岡田 晃

    第85回レーザ加工学会  2016  レーザ加工学会

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    Event date: 2016.6.9 - 2016.6.10

    Language:Japanese   Presentation type:Poster presentation  

    Venue:大阪大学  

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  • Effect of Focusing Condition on Molten Area in Micro-welding of Borosilicate Glass by Picosecond Pulsed Laser International conference

    Yasuhiro Okamoto,Imaduddin Helmi Wan Nordin, Kenichiro Ota, Togo Shininaga, Akira Okada

    International Conference on Processing and Manufacturing of Advanced Materials (THERMEC '2016)  2016 

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    Event date: 2016.5.30 - 2016.6.3

    Language:English   Presentation type:Oral presentation (invited, special)  

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  • Investigation of Spatter Behavior in Micro-processing of Metal Sheet by Pulsed Laser International conference

    Yasuhiro Okamoto, Akira Okada, Hibiki Yamamoto, Kento Shirasaya, Jari Kolehmainen, Togo Shinonaga

    17th International Symposium on Laser Precision Microfabrication  2016  Japan Laser Processing Society

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    Event date: 2016.5.23 - 2016.5.26

    Language:English   Presentation type:Oral presentation (general)  

    Venue:西安  

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  • Fundamental Study on Separation Method of Gallium Nitride with Internal Modified Layer by Ultrashort Pulsed Laser International conference

    Motoki Ota, Yasuhiro Okamoto, Togo Shinonaga, Akira Okada

    Second Smart Laser Processing Conference  2016  Japan Laser Processing Society

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    Event date: 2016.5.17 - 2016.5.19

    Language:English   Presentation type:Poster presentation  

    Venue:Pasofico Yokohama  

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  • Effective Shielding Gas Supplying Method of Wide Area in Vertical-Position Laser Welding of Pure Titanium International conference

    Kazuo Yokohara, Yasuhiro Okamoto, Akira Okada, Hikotaro Ochiai, Ryosuke Kimura, Shozo Ono, Masayuki Akase

    Second Smart Laser Processing Conference  2016  Japan Laser Processing Society

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    Event date: 2016.5.17 - 2016.5.19

    Language:English   Presentation type:Poster presentation  

    Venue:Pasofico Yokohama  

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  • Shape Change of Periodic Nanostructures Produced with Ultrashort Pulsed Laser on Titanium Surface International conference

    Togo Shinonaga, Shono Kinoshita, Yasuhiro Okamoto, Akira Okada

    Second Smart Laser Processing Conference  2016  Japan Laser Processing Society

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    Event date: 2016.5.17 - 2016.5.19

    Language:English   Presentation type:Oral presentation (general)  

    Venue:Pasofico Yokohama  

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  • Insulation Characteristics and Visibility of Transparent Conductive Film Containing Silver Nanowires by Nanosecond Pulsed Laser International conference

    Masafumi Oshita, Norio Nishi, Yasuhiro Okamoto, Togo Shinonaga, Akira Okada

    Second Smart Laser Processing Conference  2016  Japan Laser Processing Society

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    Event date: 2016.5.17 - 2016.5.19

    Language:English   Presentation type:Poster presentation  

    Venue:Pasofico Yokohama  

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  • マルチワイヤ放電スライシング法におけるグループ給電方式の高精度化

    岡本康寛

    平成27年度特別電源所在県科学技術振興事業研究成果発表会  2016  岡山県

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    Event date: 2016.3.18

    Language:Japanese   Presentation type:Poster presentation  

    Venue:岡山プラザルホテル  

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  • 銅の微細レーザ溶接において試料表面状態が光吸収特性に及ぼす影響

    井上礼輝,和田卓也,岡本康寛,岡田 晃,中芝伸一,酒川友一

    2016年度精密工学会春季大会学術講演会  2016  精密工学会

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    Event date: 2016.3.15 - 2016.3.17

    Language:Japanese   Presentation type:Oral presentation (general)  

    Venue:東京理科大学  

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  • 純Ti基盤に形成した超短パルスレーザ誘起ナノ周期構造にレーザ照射パラメータが及ぼす影響

    木下 奨之,篠永東吾,岡本康寛,岡田晃

    日本機械学会中国四国支部第54期講演会  2016  日本機械学会

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    Event date: 2016.3.9

    Language:Japanese   Presentation type:Oral presentation (general)  

    Venue:愛媛大学  

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  • グループ給電方式を用いたマルチワイヤ放電スライシング法の加工特性評価

    池田崇之,岡本康寛,岡田 晃,栗原治弥,木戸正孝

    日本機械学会中国四国支部第54期講演会  2016  日本機械学会

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    Event date: 2016.3.9

    Language:Japanese   Presentation type:Oral presentation (general)  

    Venue:愛媛大学  

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  • ナノ秒レーザを用いた鉄系材料の除去加工におけるパルス幅の影響

    伊藤瑞菜,篠永東吾,岡本康寛,岡田晃

    日本機械学会中国四国支部第54期講演会  2016  日本機械学会

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    Event date: 2016.3.9

    Language:Japanese   Presentation type:Oral presentation (general)  

    Venue:愛媛大学  

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  • 410 Effect of Laser Parameters on Ultrashort Pulsed Laser Induced Periodic Nanostructure Formed on Pure Titanium Plate

    KINOSHITA Shono, SHINONAGA Togo, OKAMOTO Yasuhiro, OKADA Akira

    2016.2.26  The Japan Society of Mechanical Engineers

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    Event date: 2016.2.26

    Language:Japanese  

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  • 412 Effect of Pulse Duration on Material Removal of Iron by ns Pulsed Laser

    ITO Mizuna, SHINONAGA Togo, OKAMOTO Yasuhiro, OKADA Akira

    2016.2.26  The Japan Society of Mechanical Engineers

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    Event date: 2016.2.26

    Language:Japanese  

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  • 409 Evaluation of Multi-wire EDM Slicing Characteristics with Group Power Supplying Method

    IKEDA Takayuki, OKAMOTO Yasuhiro, OKADA Akira, KURIHARA Haruya, KIDO Masataka

    2016.2.26  The Japan Society of Mechanical Engineers

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    Event date: 2016.2.26

    Language:Japanese  

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  • ピコ秒パルスレーザを用いたガラスの微細溶接特性に及ぼす集光条件の影響

    22nd Symposium on Micorjoining and Assembly Technology in Electronics  2016 

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    Event date: 2016.2.2 - 2016.2.3

    Language:Japanese   Presentation type:Oral presentation (general)  

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  • ナノ秒パルスレーザを用いた銀ナノワイヤ透明導電膜の絶縁特性と表面状態

    大下雅史,西 則男,岡本康寛,岡田 晃,篠永東吾

    第84回レーザ加工学会  2016 

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    Event date: 2016.1.19 - 2016.1.20

    Language:Japanese   Presentation type:Poster presentation  

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  • パルスレーザによる微細溶接 -銅の光吸収特性およびガラスとシリコンの接合- Invited

    岡本康寛

    2015年度精密工学会秋季大会学術講演会  2015.9.5  精密工学会

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    Event date: 2015.9.4 - 2015.9.6

    Language:Japanese   Presentation type:Oral presentation (keynote)  

    Venue:東北大学  

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  • ピコ秒パルスレーザを用いたガラスの微細溶接における集光特性の効果

    太田元基,竹國友裕,岡本康寛,岡田 晃

    2015年度精密工学会秋季大会学術講演会  2015  精密工学会

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    Event date: 2015.9.4 - 2015.9.6

    Language:Japanese   Presentation type:Oral presentation (general)  

    Venue:東北大学  

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  • 純チタンの水平方向レーザ溶接におけるアルゴンガスシールド性能向上の検討

    横原和男,岡本康寛,岡田 晃,落合彦太郎,木村陵介,小野昇造,赤瀬雅之

    第83回レーザ加工学会論文集  2015  レーザ加工学会

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    Event date: 2015.6.11 - 2015.6.12

    Language:Japanese   Presentation type:Oral presentation (general)  

    Venue:大阪大学  

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  • レーザを用いた多層化人工皮膚の微細穴加工法の検討

    朝子毅一,岡本康寛,岡田 晃,皆木省吾,前田直人,潘 秋月,神 桂二,西川悟郎

    2015年度精密工学会春季大会学術講演会  2015  精密工学会

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    Event date: 2015.3.17 - 2015.3.19

    Language:Japanese   Presentation type:Oral presentation (general)  

    Venue:東洋大学  

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  • ナノ秒パルスファイバレーザを用いた銀ナノワイヤ透明導電膜の加工特性に関する検討

    大下雅史,西 則男,横山豪人,岡本康寛,岡田 晃

    2015年度精密工学会春季大会学術講演会  2015  精密工学会

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    Event date: 2015.3.17 - 2015.3.19

    Language:Japanese   Presentation type:Oral presentation (general)  

    Venue:東洋大学  

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  • 大面積電子ビーム照射を用いたアルミナ薄膜形成における成膜メカニズムの検討

    高田将司,岡田 晃,岡本康寛,井上基弘,佐野定男

    2015年度精密工学会春季大会学術講演会  2015  精密工学会

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    Event date: 2015.3.17 - 2015.3.19

    Language:Japanese   Presentation type:Oral presentation (general)  

    Venue:東洋大学  

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  • グループ給電方式を用いた マルチワイヤ放電スライシング法の安定化

    岡本康寛

    平成26年度特別電源所在県科学技術振興事業研究成果発表会  2015  岡山県

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    Event date: 2015.3.16

    Language:Japanese   Presentation type:Poster presentation  

    Venue:岡山プラザルホテル  

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  • Fundamental Study on Multi-wire EDM Slicing with Group Power Supplying Method

    OTANI Takuya, OKAMOTO Yasuhiro, OKADA Akira, SUZUKI Akitoshi, KIDO Masataka, KURIHARA Haruya

    2015.2.27  The Japan Society of Mechanical Engineers

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    Event date: 2015.3.6

    Language:Japanese   Presentation type:Oral presentation (general)  

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  • Formation of Chromium Containing Layer by EDM with Chromium Powder Mixed Fluid

    TOSHIMITSU Ryota, IWASAKI Shuhei, OKADA Akira, OKAMOTO Yasuhiro

    2015.2.27  The Japan Society of Mechanical Engineers

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    Event date: 2015.3.6

    Language:Japanese   Presentation type:Oral presentation (general)  

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    Other Link: http://ci.nii.ac.jp/ncid/AN00360626

  • 純チタンの横向き姿勢レーザ微細溶接におけるシールドガス供給方法の検討

    横原 和男,白鞘 健人,岡本 康寛,岡田 晃,落合 彦太郎,木村 陵介,小野 昇造

    日本機械学会中国四国支部第53期講演会  2015  日本機械学会

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    Event date: 2015.3.6

    Language:Japanese   Presentation type:Oral presentation (general)  

    Venue:近畿大学工学部(呉)  

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  • マルチワイヤ放電スライシング法におけるグループ給電方式の開発

    岡本康寛,岡田,晃,鈴木彰隼,大谷卓也

    岡山大学知恵の見本市  2014  岡山大学

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    Event date: 2014.11.14

    Language:Japanese   Presentation type:Poster presentation  

    Venue:岡山  

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  • グループ給電方式によるマルチワイヤ放電スライシング法 International conference

    岡本康寛,岡田,晃,鈴木彰隼,大谷卓也

    第16回国際工作機械技術者会議ポスターセッション  2014  日本工作機械工業会

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    Event date: 2014.11.1 - 2014.11.2

    Language:Japanese   Presentation type:Poster presentation  

    Venue:東京ビックサイト  

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  • Effect of Surrounding Gas Condition on Surface Integrity in Micro-drilling of SiC by ns Pulsed Laser International conference

    Yasuhiro Okamoto, Kiichi Asako, Norio Nishi, Tomokazu Sakagawa, Akira Okada

    9th International Conference on Photo-Excited Processes and Applications  2014 

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    Event date: 2014.9.30 - 2014.10.3

    Language:English   Presentation type:Poster presentation  

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  • 矩形ファイバを用いたナノ秒パルスレーザによるZnO膜の除去加工

    西 則男,横山豪人,岡本康寛,岡田 晃,中芝伸一,酒川友一

    2014年度精密工学会秋季大会学術講演会  2014  精密工学会

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    Event date: 2014.9.16 - 2014.9.18

    Language:Japanese   Presentation type:Oral presentation (general)  

    Venue:鳥取大学  

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  • Study on Applicability of Large-area EB Irradiation to Micro-deburring International conference

    Tomoaki Miyoshi, Akira Okada and Yasuhiro Okamoto

    International Conference on Machining, Materials and Mechanical Technologies  2014 

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    Event date: 2014.9.1 - 2014.9.4

    Language:English   Presentation type:Oral presentation (general)  

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  • Influence of Nozzle Jet Flushing on Wire Deflection and Breakage in Wire EDM International conference

    Takuro Konishi, Sameh Habib, Akira Okada, Yasuhiro Okamoto and Haruya Kurihara

    International Conference on Machining, Materials and Mechanical Technologies  2014 

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    Event date: 2014.9.1 - 2014.9.4

    Language:English   Presentation type:Oral presentation (general)  

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  • Study on Surface Characteristics of EDMed Surface with Nickel Powder Mixed Fluid International conference

    Syuhei Iwasaki, Ryoji Kitada, Akira Okada and Yasuhiro Okamoto

    International Conference on Machining, Materials and Mechanical Technologies  2014 

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    Event date: 2014.9.1 - 2014.9.4

    Language:English   Presentation type:Oral presentation (general)  

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  • Effects of Focusing Condition on Micro-welding Characteristics of Borosilicate Glass by Picosecond Pulsed Laser International conference

    Tomohiro Tekekuni, Yasuhiro Okamoto, Takahiro Fujiwara, Akira Okada and Isam Miyamoto

    International Conference on Machining, Materials and Mechanical Technologies  2014 

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    Event date: 2014.9.1 - 2014.9.4

    Language:English   Presentation type:Oral presentation (general)  

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  • 溶接困難材料の微細レーザ溶接

    岡本康寛,岡田 晃

    第107回マイクロ接合研究委員会  2014  溶接学会

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    Event date: 2014.7.4

    Language:Japanese   Presentation type:Oral presentation (invited, special)  

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  • Effect of Wavelength and Pulse Duration in Laser Micro-welding of Glass and Monocrystalline Silicon International conference

    Imaduddin Helmin bin Wan Nordin, Yasuhiro Okamoto, Isamu Miyamoto and Akira Okada

    15th International Symposium on Laser Precision Microfabrication (LPM2014)  2014 

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    Event date: 2014.6.17 - 2014.6.20

    Language:English   Presentation type:Oral presentation (general)  

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  • パルスグリーンYAGレーザを用いた銅の微細溶接における吸収特性の評価

    和田卓也,高井淳生,岡本康寛,岡田 晃,中芝伸一,酒川友一

    2014年度精密工学会春季大会学術講演会  2014  精密工学会

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    Event date: 2014.3.18 - 2014.3.20

    Language:Japanese   Presentation type:Oral presentation (general)  

    Venue:東京大学  

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  • 大面積パルス電子ビーム照射による凸部形状の変化

    幸山功輝,岡田 晃,岡本康寛

    2014年度精密工学会春季大会学術講演会  2014  精密工学会

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    Event date: 2014.3.18 - 2014.3.20

    Language:Japanese   Presentation type:Oral presentation (general)  

    Venue:東京大学  

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  • 装置構成の簡素化を目指したマルチワイヤ放電スライシング法における給電方式の開発

    岡本康寛

    平成25年度特別電源所在県科学技術振興事業研究成果発表会  2014  岡山県

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    Event date: 2014.3.13

    Language:Japanese   Presentation type:Poster presentation  

    Venue:岡山ロイヤルホテル  

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  • Fundamental investigation of Laser Micro-drilling for Multi-layered Artificial Skin

    ASAKO Kiichi, OKAMOTO Yasuhiro, OKADA Akira, MINAGI Shogo, MAEDA Naoto, PAN Qiuyue, JIN Keiji, NISHIGAWA Goro

    2014.3.8  The Japan Society of Mechanical Engineers

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    Event date: 2014.3.8

    Language:Japanese   Presentation type:Oral presentation (general)  

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  • Fundamental Study on Micro-welding of Super Thermal Conductive Copper Graphite Composite by Pulsed Nd:YAG Laser

    2014.3.8  The Japan Society of Mechanical Engineers

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    Event date: 2014.3.8

    Language:Japanese   Presentation type:Oral presentation (general)  

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  • Study on Micro-deburing by Pulsed Large-area EB Irradiation

    2014.3.6  The Japan Society of Mechanical Engineers

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    Event date: 2014.3.8

    Presentation type:Oral presentation (general)  

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  • パルスレーザーを用いた微細溶接技術

    岡本康寛,中芝伸一,岡田 晃

    レーザー学会第34回年次大会  2014  レーザー学会

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    Event date: 2014.1.20

    Language:Japanese   Presentation type:Oral presentation (invited, special)  

    Venue:小倉  

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  • Novel Micro-welding of Silicon and Glass by Ultrashort Pulsed Laser International conference

    Yasuhiro Okamoto, Isamu Miyamoto, Jorma Vihinen and Akira Okada

    8th International Conference on Processing and Manufacturing of Advanced Materials (THERMEC '2013)  2013 

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    Event date: 2013.12.2 - 2013.12.6

    Language:English   Presentation type:Oral presentation (invited, special)  

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  • 大面積電子ビーム照射による金属薄膜形成に関する研究

    高田将司,岡田 晃,岡本康寛

    2013年度精密工学会中国四国支部-広島地方学術講演会  2013  精密工学会中国四国支部

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    Event date: 2013.11.30

    Language:Japanese   Presentation type:Oral presentation (general)  

    Venue:島根大学  

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  • ピコ秒パルスレーザを用いたホウケイ酸ガラスに対する微細溶融溶接法の検討

    藤原隆宏,竹國友裕,岡本康寛,岡田 晃

    2013年度精密工学会中国四国支部-広島地方学術講演会  2013  精密工学会中国四国支部

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    Event date: 2013.11.30

    Language:Japanese   Presentation type:Oral presentation (general)  

    Venue:島根大学  

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  • 大面積電子ビーム照射法を用いた微細バリ取り

    米原 甫,三好友陽,岡田 晃,岡本康寛

    2013年度精密工学会中国四国支部-広島地方学術講演会  2013  精密工学会中国四国支部

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    Event date: 2013.11.30

    Language:Japanese   Presentation type:Oral presentation (general)  

    Venue:島根大学  

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  • ワイヤ放電加工におけるノズルフラッシングに起因するワイヤ撓みの検討

    小西拓郎,岡田 晃,岡本康寛

    2013年度精密工学会中国四国支部-広島地方学術講演会  2013  精密工学会中国四国支部

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    Event date: 2013.11.30

    Language:Japanese   Presentation type:Oral presentation (general)  

    Venue:島根大学  

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  • Investigation of Phenomenon in Removal Processing of TCO Film by ns Pulsed Fiber Laser

    Yokoyama Takehito, Okamoto Yasuhiro, Okada Akira, Nakashiba Shin-ichi, Sakagawa Tomokazu

    JSPE Semestrial Meeting  2013.9  The Japan Society for Precision Engineering

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    Event date: 2013.9.12 - 2013.9.14

    Language:Japanese   Presentation type:Oral presentation (general)  

    TCO (Transparent Conductive Oxide) film has widely been used in many industrial fields because of its excellent conductive characteristics and the transparency at the visible wavelength. However, it is required to perform the processing without any damages to other thin layers except for a removal object and to apply for various kinds of TCO film. The phenomenon in scribing ZnO film was investigated by the observation of scribed groove and removal processing.

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    Other Link: https://jlc.jst.go.jp/DN/JALC/10034517863?from=CiNii

  • レーザー加工による多層化人工皮膚への皮膚蒸泄水分排出孔の形成に関する研究

    前田直人,潘 秋月,岡本康寛,岡田 晃,神 桂二,西川悟郎,皆木省吾

    日本顎顔面補綴学会第30回学術大会  2013  日本顎顔面補綴学会

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    Event date: 2013.6.21

    Language:Japanese   Presentation type:Oral presentation (general)  

    Venue:奥羽大学  

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  • トラック形状断面ワイヤ電極を用いたSiCの高品位放電スライシング法の開発

    岡本康寛

    平成24年度特別電源所在県科学技術振興事業研究成果発表会  2013  岡山県

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    Event date: 2013.3.15

    Language:Japanese   Presentation type:Poster presentation  

    Venue:岡山ロイヤルホテル  

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  • レーザ微細穴加工時におけるスパッタの3次元挙動と冷却特性

    白鞘 健人,山本 響,岡本 康寛,岡田 晃

    2013年度精密工学会春季大会学術講演会  2013  精密工学会

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    Event date: 2013.3.13 - 2013.3.15

    Language:Japanese   Presentation type:Oral presentation (general)  

    Venue:東京工業大学  

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  • 大面積電子ビーム照射による凸形状変化に関する基礎的研究

    幸山功輝,藤田智弘,岡田晃,岡本康寛

    日本機械学会中国四国学生会第43回学生員卒業研究発表講演会  2013  日本機械学会

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    Event date: 2013.3.7

    Presentation type:Oral presentation (general)  

    Venue:高知工科大学  

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  • 金属薄板のレーザ微細溶接においてビード形状が熱変形に及ぼす影響

    音羽皇紀,松岡慧,岡本康寛,岡田晃

    日本機械学会中国四国学生会第43回学生員卒業研究発表講演会  2013  日本機械学会

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    Event date: 2013.3.7

    Presentation type:Oral presentation (general)  

    Venue:高知工科大学  

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  • 多結晶Siインゴットのマルチワイヤ放電スライシング法におけるプロセス速度の検討

    石村聡美,木村敦史,岡田晃,岡本康寛

    日本機械学会中国四国学生会第43回学生員卒業研究発表講演会  2013  日本機械学会

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    Event date: 2013.3.7

    Presentation type:Oral presentation (general)  

    Venue:高知工科大学  

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  • スクエアファイバとナノ秒パルスファイバレーザによるTCO膜の除去加工

    高橋直也,岡本康寛,岡田晃,中芝伸一,酒川友一

    第78回レーザ加工学会  2012  レーザ加工学会

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    Event date: 2012.12.13 - 2012.12.14

    Language:Japanese   Presentation type:Poster presentation  

    Venue:関西大学  

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  • Analysis of Fluid Force Acting on Wire Electrode by Jet Flushing in Wire EDM

    KURIYAMA Kazuki, OKADA Akira, OKAMOTO Yasuhiro

    2012.12.6 

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    Event date: 2012.12.6

    Language:Japanese  

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  • パルスファイバレーザによるサファイアの分割法

    岡本康寛

    岡山大学知恵の見本市2012  2012 

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    Event date: 2012.11.2

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  • Study on Crater Generation Mechanism in Large-area Electron Beam Irradiation of Al-Si Alloy

    FUJITA Tomohiro, OKADA Akira, OKAMOTO Yasuhiro, CLARE Adam

    2012.9  The Japan Society of Mechanical Engineers

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    Event date: 2012.10.27 - 2012.10.28

    Language:Japanese   Presentation type:Oral presentation (general)  

    Al-Si alloy has been widely used for engine pistons and cylinders because of its light weight and high wear resistance. It was clarified that the wear resistance could be increased by large-area EB irradiation. However, many craters were generated on the EB irradiated surface. If the crater generation could be reduced, further improvement in wear resistance might be possible. In this study, heat conduction analysis of the Al-Si alloy surface was carried out in order to discuss the temperature distribution and the crater generation mechanism. Then a two-staged large-area EB irradiation method, in which the craters generated by first high energy condition were smoothed by second low energy condition was tried on the basis of the analysis results.

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  • Fundamental Study on Micro-welding of Copper by Green Pulsed YAG Laser

    TAKAI Sunao, OKAMOTO Yasuhiro, OKADA Akira, NAKASHIBA Shin-ichi, SAKAGAWA Tomokazu

    2012.9  The Japan Society of Mechanical Engineers

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    Event date: 2012.10.27 - 2012.10.28

    Language:Japanese   Presentation type:Oral presentation (general)  

    It is required to perform the effective and stable laser welding for copper material, since copper became more important material for electrical products because of its excellent electrical and thermal conductivity. In micro-welding of 1.0mm thickness copper plate by pulsed green laser, a key hole welding was successfully performed by 1.0kW peak power at spot diameter less than 200μm. The freequency doubled pulsed laser improved the processing efficiency of copper welding, and narrow and deep weld bead was stably obtained. Penetration depth increased with decreasing of the spot diameter and increasing the pulse duration. The generation of porosity could be reduced by controlling the pulse waveform, and the longer pulse duration was also effective to remove the remaining bubbles. The pulse waveform played an important role on the stability of welding phenomenon, and the maximum peak at the early period could lead to the stabilization of penetration depth.

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  • Study on Crater Generation Mechanism in Large-area Electron Beam Irradiation of Al-Si Alloy

    FUJITA Tomohiro, OKADA Akira, OKAMOTO Yasuhiro, CLARE Adam

    The ... Manufacturing & Machine Tool Conference  2012.10.27  The Japan Society of Mechanical Engineers

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    Event date: 2012.10.27

    Language:Japanese   Presentation type:Oral presentation (general)  

    Al-Si alloy has been widely used for engine pistons and cylinders because of its light weight and high wear resistance. It was clarified that the wear resistance could be increased by large-area EB irradiation. However, many craters were generated on the EB irradiated surface. If the crater generation could be reduced, further improvement in wear resistance might be possible. In this study, heat conduction analysis of the Al-Si alloy surface was carried out in order to discuss the temperature distribution and the crater generation mechanism. Then a two-staged large-area EB irradiation method, in which the craters generated by first high energy condition were smoothed by second low energy condition was tried on the basis of the analysis results.

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  • 連続発振LD重畳がアルミニウム合金の微細レーザ溶接特性に及ぼす影響

    原田昌宜,岡本康寛,岡田 晃,中芝伸一,酒川友一

    2012年度精密工学会中国四国支部-島根地方学術講演会-講演論文集  2012  精密工学会中国四国支部

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    Event date: 2012.10.6

    Language:Japanese   Presentation type:Oral presentation (general)  

    Venue:島根大学  

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  • Investigation of Micro-drilling Characteristics for SiC by Harmonics of YAG Laser

    Urushibata Shin, Okamoto Yasuhiro, Okada Akira, Nakashiba Sinichi, Sakagawa Tomokazu

    2012.9.14  The Japan Society for Precision Engineering

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    Event date: 2012.9.14 - 2012.9.16

    Language:Japanese   Presentation type:Oral presentation (general)  

    Silicon carbide is expected as a material for power devices in the next generation. The superior processing technique is important in order to utilize the high potential of silicon carbide. The laser processing is useful method for micro-machining. However, it is reported that the laser induced plasma has a great influence on machining characteristics. Therefore, micro-machining characteristics of silicon carbide by the harmonic of Nd:YAG laser were experimentally investigated in the viewpoints of wavelength and the surrounding condition. Moreover, micro-machining characteristics of silicon carbide by the harmonics of Nd:YAG laser were discussed by the observation of the plasma on the specimen surface.

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    Other Link: https://jlc.jst.go.jp/DN/JALC/10034510147?from=CiNii

  • Evaluation of Wire Movement in Fine Wire EDM by High-speed Observation

    Ichii Sho, Okada Akira, Okamoto Yasuhiro

    2012.9.14  The Japan Society for Precision Engineering

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    Event date: 2012.9.14 - 2012.9.16

    Language:Japanese   Presentation type:Oral presentation (general)  

    The wire movement in fine wire EDM using thin wire would affect the machining shape accuracy but it has not yet been made clear sufficiently. In this study, the movements of wire electrode are directly observed by using a high-speed video camera in order to clarify the wire vibration in fine wire EDM. Experimental results showed that the wire behavior depended mainly on the wire tension and discharge frequency, and it was almost 1st order mode string vibration.

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    Other Link: https://jlc.jst.go.jp/DN/JALC/10034507598?from=CiNii

  • 大面積電子ビーム照射による微細バリ取りの基礎的研究

    米原 甫,岡田 晃 , 岡本康寛

    2012年度精密工学会秋季大会学術講演会  2012  精密工学会

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    Event date: 2012.9.14 - 2012.9.16

    Language:Japanese   Presentation type:Oral presentation (general)  

    Venue:福岡県  

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  • 金属の微細レーザ加工におけるスパッタ飛散速度の測定

    山本 響,岡本康寛,岡田 晃,白鞘健人,ヤリ コレマイネン

    第77回レーザ加工学会  2012  レーザ加工学会

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    Event date: 2012.5.24 - 2012.5.25

    Language:Japanese   Presentation type:Poster presentation  

    Venue:大阪大学  

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  • 特殊ワイヤ電極を用いたSiCの高能率・高品位電解アシステッド放電スライシング

    岡本康寛

    平成23年度特別電源所在県科学技術振興事業研究成果発表会  2012  岡山県

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    Event date: 2012.3.15

    Language:Japanese   Presentation type:Poster presentation  

    Venue:岡山ロイヤルホテル  

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  • Measurement of the Spatter Velocity in Fine Laser Cutting

    Jari Tapani Kolehmainen, Yasuhiro Okamoto, Hibiki Yamamoto, Akira Okada and , Timo Tapani Viitanen

    2012 

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    Event date: 2012.3.14 - 2012.3.16

    Language:English   Presentation type:Oral presentation (general)  

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  • トラック形状断面ワイヤ電極を用いたSiCの放電スライシングに関する試み

    木村 敦史,岡本康寛,岡田 晃,岳 志輝,大矢 純,山内俊之

    2012年度精密工学会春季大会学術講演会  2012  精密工学会

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    Event date: 2012.3.14 - 2012.3.16

    Language:Japanese   Presentation type:Oral presentation (general)  

    Venue:東京都  

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  • Effect of Machined Kerf Length on Debris Exclusion in Wire EDM

    KURIYAMA Kazuki, OKADA Akira, OKAMOTO Yasuhiro, FUJIMOTO Takuya

    2012.2.28  The Japan Society of Mechanical Engineers

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    Event date: 2012.2.28

    Language:Japanese  

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  • パルスファイバーレーザによるサファイアの高アスペクト比内部改質層の形成

    高橋健太,岡本康寛,岡田 晃

    第76回レーザ加工学会  2011  レーザ加工学会

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    Event date: 2011.12.5 - 2011.12.6

    Language:Japanese   Presentation type:Poster presentation  

    Venue:関西大学  

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  • アルミニウムバッテリーケースの高効率・高品位レーザ溶接法

    岡本康寛

    岡山大学知恵の見本市2011  2011 

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    Event date: 2011.11.2

    Language:Japanese   Presentation type:Poster presentation  

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  • 冷却ガスを用いた半導体パッケージの高品位レーザダイシング

    山本 響,岡本康寛,岡田 晃,北田良二,池田卓也

    2011年度精密工学会岡山地方学術講演会  2011  精密工学会中国四国支部

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    Event date: 2011.10.8 - 2011.10.9

    Language:Japanese   Presentation type:Oral presentation (general)  

    Venue:岡山大学  

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  • 大面積電子ビーム照射によるニッケルバインダ超硬合金の表面改質

    三角周平,郭 洪閣,岡田 晃,岡本康寛

    2011年度精密工学会岡山地方学術講演会  2011  精密工学会中国四国支部

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    Event date: 2011.10.8 - 2011.10.9

    Language:Japanese   Presentation type:Oral presentation (general)  

    Venue:岡山大学  

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  • トラック形状断面ワイヤ電極を用いた放電スライシングの関する基礎的検討

    岳 志輝,岡本康寛,岡田 晃,木村敬史,大矢 純,山内俊之

    2011年度精密工学会岡山地方学術講演会  2011  精密工学会中国四国支部

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    Event date: 2011.10.8 - 2011.10.9

    Language:Japanese   Presentation type:Oral presentation (general)  

    Venue:岡山大学  

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  • 加工液へのAl粉末混入が放電加工面の離型性に及ぼす影響

    河田 良介,周 志全,岡田 晃,岡本康寛

    2011年度精密工学会岡山地方学術講演会  2011  精密工学会中国四国支部

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    Event date: 2011.10.8 - 2011.10.9

    Language:Japanese   Presentation type:Oral presentation (general)  

    Venue:岡山大学  

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  • Effects of Superposed Continuous Diode Laser on Welding Phenomenon in Welding of Aluminum Alloy by Pulsed Nd:YAG Laser

    Nakashiba Shin-ichi, Okamoto Yasuhiro, Sakagawa Tomokazu, Miura Kazuya, Okada Akira, Uno Yoshiyuki

    JSPE Semestrial Meeting  2011.9.20  The Japan Society for Precision Engineering

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    Event date: 2011.9.20 - 2011.9.22

    Language:Japanese   Presentation type:Oral presentation (general)  

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    Other Link: https://jlc.jst.go.jp/DN/JALC/10034498629?from=CiNii

  • Internal Modification Technique of Sapphire by Picosecond Pulsed Fiber Laser

    Takahashi Kenta, Okamoto Yasuhiro, Okada Akira

    JSPE Semestrial Meeting  2011.9.20  The Japan Society for Precision Engineering

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    Event date: 2011.9.20 - 2011.9.22

    Language:Japanese   Presentation type:Oral presentation (general)  

    It is important to reduce the edge damage in cleavage of sapphire substrate for cost reduction. In this study, the internal modification technique of a sapphire substrate by picosecond pulsed fiber laser were investigated. Internal modification of sapphire with a high aspect ratio such as 5µm width and 150µm height were successfully performed by the irradiation from the epitaxial layer side. A sapphire wafer of 0.4 mm thickness could be broken from the internal modified line without less damage of the epitaxial layer.

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    Other Link: https://jlc.jst.go.jp/DN/JALC/10034498674?from=CiNii

  • ワイヤ放電加工における加工液流れのCFD解析(第5報)-工作物厚さと加工切込み長さの影響? -

    藤本卓也,岡田 晃,岡本康寛,宇野義幸

    2011年度精密工学会秋季大会学術講演会 

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    Event date: 2011.9.20 - 2011.9.22

    Language:Japanese   Presentation type:Oral presentation (general)  

    Venue:金沢大学  

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  • MOPA方式パルスファイバレーザを用いた金型材料の表面処理法

    岡本康寛,岡田 晃,高橋健太,角井素貴

    第16回岡山リサーチパーク研究・展示発表会  2011 

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    Event date: 2011.9.1

    Language:Japanese   Presentation type:Poster presentation  

    Venue:岡山市  

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  • レーザによる材料加工と最新技術

    岡本康寛

    岡山県精密生産技術研究会 平成23年度第2回セミナー  2011  岡山県精密生産技術研究会

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    Event date: 2011.8.26

    Language:Japanese   Presentation type:Oral presentation (invited, special)  

    Venue:岡山市  

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  • 微細加工用パルス幅可変ファイバレーザ

    角井素貴,田中裕士,岡本康寛,宇野義幸

    第75回レーザ加工学会  2011  レーザ加工学会

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    Event date: 2011.5.11 - 2011.5.12

    Language:Japanese   Presentation type:Oral presentation (invited, special)  

    Venue:関西大学  

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  • YAG高調波による半導体材料の微細加工特性とその現象の検討

    平野孝義,岡本康寛,宇野義幸

    2011年度精密工学会春季大会学術講演会  2011  精密工学会

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    Event date: 2011.3.15

    Language:Japanese   Presentation type:Oral presentation (general)  

    Venue:東京都  

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  • 大面積電子ビーム照射における工作物温度の非定常熱伝導解析

    藤田智弘,岡田 晃,岡本康寛,宇野義幸

    2011年度精密工学会春季大会学術講演会  2011  精密工学会

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    Event date: 2011.3.15

    Language:Japanese   Presentation type:Oral presentation (general)  

    Venue:東京都  

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  • トラック形状断面ワイヤ電極による放電スライシングの試み

    西村 淳,岡本康寛,岡田 晃,宇野義幸,岳 志輝,大矢純,山内俊之

    2011年度精密工学会春季大会学術講演会  2011  精密工学会

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    Event date: 2011.3.14

    Language:Japanese   Presentation type:Oral presentation (general)  

    Venue:東京都  

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  • SiCの高能率・高品位電解アシステッド放電スライシング法の基盤技術開発

    岡本康寛

    平成22年度特別電源所在県科学技術振興事業研究成果発表会  2011  岡山県

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    Event date: 2011.3.9

    Language:Japanese   Presentation type:Poster presentation  

    Venue:岡山ロイヤルホテル  

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  • 902 Effect of Tilting Flushing Nozzle on Debris Exclusion in Wire EDM

    MYOKEN Takashi, OKADA Akira, OKAMOTO Yasuhiro, FUJIMOTO Takuya, UNO Yoshiyuki

    2011.2.23  The Japan Society of Mechanical Engineers

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    Event date: 2011.2.23

    Language:Japanese  

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  • Micro-welding of high thermal conductive material aluminum-graphite composite by pulsed Nd:YAG laser "jointly worked"

    Mohd Idris Shah Ismail, Yasuhiro Okamoto, Akira Okada, Yoshiyuki Uno, Muhaizad Mukhtar

    Proceedings of 12th International Symposium on Laser Precision Microfabrication  2011 

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    Event date: 2011

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  • 電解アシステッドマルチワイヤ放電スライシング法

    岡本康寛

    岡山大学新技術説明会  2010  岡山大学

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    Event date: 2010.12.7

    Language:Japanese  

    Venue:JST本部  

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  • 薄板のレーザ精密切断加工におけるアシストガスの効果的供給方法

    山本 響,岡本康寛,宇野義幸

    第74回レーザ加工学会  2010  レーザ加工学会

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    Event date: 2010.12.6 - 2010.12.7

    Language:Japanese   Presentation type:Poster presentation  

    Venue:東京大学  

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  • 超短パルスレーザを用いたガラスの微細溶接法?溶融領域の強度評価?

    山本 敬史,岡本 康寛,宇野 義幸,宮本 勇,K.ツベチェク,M.シュミット

    第74回レーザ加工学会  レーザ加工学会

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    Event date: 2010.12.6 - 2010.12.7

    Language:Japanese   Presentation type:Poster presentation  

    Venue:東京大学  

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  • 超短パルスレーザを用いたガラスの微細溶接法における溶融領域の評価

    山本 敬史,岡本 康寛,宇野 義幸,宮本 勇,K.ツベチェク,M.シュミット

    日本機械学会第8回生産加工・工作機械部門講演会  2010  日本機械学会

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    Event date: 2010.11.19 - 2010.11.20

    Language:Japanese   Presentation type:Oral presentation (general)  

    Venue:岡山大学  

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  • YAG高調波による単結晶シリコンの微細加工特性とその現象の検討

    平野 孝幸,岡本 康寛,宇野 義幸,酒川 友一,中芝 伸一

    日本機械学会第8回生産加工・工作機械部門講演会  2010  日本機械学会

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    Event date: 2010.11.19 - 2010.11.20

    Language:Japanese   Presentation type:Oral presentation (general)  

    Venue:岡山大学  

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  • A24 Evaluation of Molten Zone in Micro-welding of Glass by Ultra-short Pulse Laser

    Yamamoto Keishi, Okamoto Yasuhiro, Uno Yoshiyuki, Cvecek Kristian, Schmid Michael

    The ... Manufacturing & Machine Tool Conference  2010.11.19  The Japan Society of Mechanical Engineers

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    Event date: 2010.11.19

    Language:Japanese  

    Fusion welding is well known as the most promising technique in glass joining, since joining can be accomplished without any intermediate layer and mechanical contact. High precision, small heat-affected zone (HAZ) and small shock-affected zone (SAZ) by ultra-short pulsed laser make it possible to perform the joining process with minimal damages to the surrounding area. However, there still remained a lot of things to be clarified in this process, since glass materials are very sensitive to temperature gradients. In this study, molten zones created by ultra-short pulsed laser in a fused silica glass were experimentally investigated. Laser irradiation was carried out inside the glass under various processing conditions. Molten zone was observed visually, and its mechanical strength was measured using three points bending test. The strength of molten zone was almost equal to the base material, and high strength could be obtained at low velocity and high pulse repetition rate condition.

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  • A33 Investigation of Micro-machining Characteristics and Phenomenon of Monocrystalline Silicon by Harmonics of Nd:YAG Laser

    Hirano Takayuki, Okamoto Yasuhiro, Uno Yoshiyuki, Sakagawa Tomokazu, Nkashiba Sin-ichi

    The ... Manufacturing & Machine Tool Conference  2010.11.19  The Japan Society of Mechanical Engineers

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    Event date: 2010.11.19

    Language:Japanese  

    Monocrystalline silicon has played an important role as semiconductors in the electronical and the electrical industries. High efficiency and high quality manufacturing process of silicon is required for the continuous development of these fields. However, debris and cracks remained on machined surface by the traditional mechanical processing because of its high brittleness. On the other hand, laser beam machining could realize the high-speed processing. However, heat affected zone and dross remained in the case of fundamental wavelength of Nd:YAG laser. In comparison, it is expected that harmonics of Nd:YAG laser make it possible to perform the high precision micro-machining with small heat affected zone and crack because of its high photon energy. In this study, the influence of wavelength and surrounding pressure was investigated with observing process behavior using a high-speed shutter camera in micro-machining of monocrystalline silicon by fundamental wavelength and harmonics of Nd:YAG laser.

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  • 半導体パッケージの高品位レーザ切断法の基礎的検討

    Muhamad Fahmi bin Mohd Noor,岡本康寛,宇野義幸,池田卓矢,北田良二

    2010年度精密工学会徳島地方学術講演会  2010  精密工学会中国四国支部

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    Event date: 2010.11.13

    Language:Japanese   Presentation type:Oral presentation (general)  

    Venue:徳島  

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  • 半導体レーザ重畳パルスYAG レーザによるアルミニウム合金の高効率微細溶接法

    宇野義幸,岡本康寛,酒川友一,三浦和也,高橋直也

    第14回国際工作機械技術者会議 JIMTOF2010「工作機械関連のニューテクノロジー」ポスター展  2010  日本工作機械工業会

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    Event date: 2010.10.28 - 2010.11.2

    Language:Japanese   Presentation type:Poster presentation  

    Venue:東京ビックサイト  

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  • 薄板のレーザ精密切断加工においてノズル形状が溶融金属の除去に及ぼす効果

    山本 響,岡本康寛,宇野義幸,鈴木博士

    2010年度精密工学会秋季大会学術講演会  2010 

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    Event date: 2010.9.27

    Language:Japanese   Presentation type:Oral presentation (general)  

    Venue:名古屋工業大学  

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  • Welding of aluminum alloy by superposition of diode laser and pulsed YAG laser

    Yasuhiro OKAMOTO, Tomokazu SAKAGAWA, Shin-ich NAKASHIBA, Yoshiyuki UNO, Kazuya MIURA

    The first mini forum of laser platform association in 2010 at Sikoku?  2010 

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    Event date: 2010.9.9

    Language:Japanese   Presentation type:Oral presentation (invited, special)  

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  • 岡山大学 特殊加工学研究室「レーザ微細加工技術」

    宇野義幸,岡田 晃,岡本康寛

    ABTEC2010度砥粒加工学会学術講演会  2010  砥粒加工学会

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    Event date: 2010.8.26 - 2010.8.28

    Language:Japanese   Presentation type:Poster presentation  

    Venue:岡山大学  

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  • 岡山大学 特殊加工学研究室「大面積電子ビーム照射による表面処理技術」

    宇野義幸,岡田 晃,岡本康寛

    ABTEC2010度砥粒加工学会学術講演会  2010  砥粒加工学会

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    Event date: 2010.8.26 - 2010.8.28

    Language:Japanese   Presentation type:Poster presentation  

    Venue:岡山大学  

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  • 岡山大学 特殊加工学研究室 「放電加工の高性能化に関する研究」

    宇野義幸,岡田 晃,岡本康寛

    ABTEC2010度砥粒加工学会学術講演会  2010  砥粒加工学会

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    Event date: 2010.8.26 - 2010.8.28

    Language:Japanese   Presentation type:Poster presentation  

    Venue:岡山大学  

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  • パルスファイバレーザの高速走査を用いた金型材料に対する表面性状制御の試み

    田中裕士,岡本康寛,宇野義幸

    ABTEC2010度砥粒加工学会学術講演会  2010  砥粒加工学会

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    Event date: 2010.8.26 - 2010.8.28

    Language:Japanese   Presentation type:Oral presentation (general)  

    Venue:岡山大学  

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  • 超短パルスレーザによるガラスの溶融溶接技術

    宮本 勇,K. ツベチェク, M. ウオルフ,岡本康寛, M. シュミット

    第73回レーザ加工学会  2010  レーザ加工学会

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    Event date: 2010.5.25 - 2010.5.26

    Language:Japanese   Presentation type:Oral presentation (invited, special)  

    Venue:大阪大学  

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  • パルスNd:YAGレーザを用いたフレキシブル基板と金属配線の直接接合

    モハマド イドリス シャ イスマイル,岡本康寛,宇野義幸

    第73回レーザ加工学会  2010  レーザ加工学会

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    Event date: 2010.5.25 - 2010.5.26

    Language:Japanese   Presentation type:Poster presentation  

    Venue:大阪大学  

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  • LD重畳パルスYAGレーザを用いたアルミニウム合金の微細溶接における予熱パルスの効果

    三浦和也,岡本康寛,宇野義幸,酒川友一,中芝伸一

    第73回レーザ加工学会  2010  レーザ加工学会

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    Event date: 2010.5.25 - 2010.5.26

    Language:Japanese   Presentation type:Poster presentation  

    Venue:大阪大学  

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  • レーザによる微細溶接

    岡本康寛

    平成22年度「半導体ネットおかやま」第1回例会  2010  岡山大学

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    Event date: 2010.5.13

    Language:Japanese   Presentation type:Oral presentation (invited, special)  

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  • 各種レーザによる透明導電膜の除去加工特性

    野原将平,岡本康寛,宇野義幸,原口 心,酒川友一

    2010年度精密工学会春季大会学術講演会  2010  精密工学会

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    Event date: 2010.3.16

    Language:Japanese   Presentation type:Oral presentation (general)  

    Venue:東京都  

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  • SiCの放電スライシングとその高性能化に関する検討

    三好博行,岡本康寛,宇野義幸,岡田 晃,高橋宏和,?村誠三,大矢純,山内俊之

    2010年度精密工学会春季大会学術講演会  2010  精密工学会

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    Event date: 2010.3.16

    Language:Japanese   Presentation type:Oral presentation (general)  

    Venue:東京都  

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  • 高能率・高品位加工を可能とする電解アシスデッド放電スライシング法の基盤技術開発

    岡本康寛

    平成21年度特別電源所在県科学技術振興事業研究成果発表会  2010  岡山県

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    Event date: 2010.3.10

    Language:Japanese   Presentation type:Poster presentation  

    Venue:岡山ロイヤルホテル  

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  • マルチワイヤ放電スライシング技術

    岡本康寛

    砥粒加工学会HEAT専門委員会 第20回研究会 「スライシング技術の最新動向」  2010  砥粒加工学会HEAT専門委員会

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    Event date: 2010.2.5

    Language:Japanese   Presentation type:Oral presentation (invited, special)  

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  • 固体レーザによる微細加工技術

    岡本康寛

    「高度先端計測を融合させた極微ものづくり産業創出事業」研究会  2010  岡山大学

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    Event date: 2010.1.19

    Language:Japanese   Presentation type:Oral presentation (invited, special)  

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  • Effects of Superposed Continuous Diode Laser on Welding Characteristics for Aluminum Alloy in Pulsed Nd:YAG Laser Welding

    Kazuya MIURA, Yasuhiro OKAMOTO, Tomokazu SAKAGAWA, Yoshiyuki UNO, Shin-ichi HARAGUCHI, Shin-ich NAKASHIBA

    Proceedings of 11th International Symposium on Laser Precision Microfabrication  2010 

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    Event date: 2010

    Language:English  

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  • 半導体パッケージの高品位レーザダイシングの試み

    池田卓矢,岡本康寛,宇野義幸,北田良二

    2009年度精密工学会山口地方学術講演会  2009  精密工学会中国四国支部

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    Event date: 2009.11.21

    Language:Japanese   Presentation type:Oral presentation (general)  

    Venue:下関  

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  • パルスファイバレーザの高速走査による金型材料の表面改質に関する基礎的研究

    田中裕士,岡本康寛,宇野義幸

    2009年度精密工学会山口地方学術講演会  2009  精密工学会中国四国支部

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    Event date: 2009.11.21

    Language:Japanese   Presentation type:Oral presentation (general)  

    Venue:下関  

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  • Fiber Laser and its Applications International conference

    Yasuhiro Okamoto

    Advanced Machining And Fabrication Technology (Amft) Research Group Meeting, Universiti Tun Hussein Onn Malaysia  2009  Universiti Tun Hussein Onn Malaysia

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    Event date: 2009.11.13

    Language:English  

    Venue:Johor  

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  • アルミニウム合金のYAGレーザ溶接におけるLD重畳の効果

    原口 心,岡本康寛,宇野義幸,酒川友一,中芝伸一

    2009年度精密工学会秋季大会学術講演会  2009 

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    Event date: 2009.9.10 - 2009.9.12

    Language:Japanese   Presentation type:Oral presentation (general)  

    Venue: