論文 - 甲藤 正人
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Debris characteristics and mitigation of a laser plasma tin-contained liquid jet/droplet targets
Kaku M., Touge S., Katto M., Kubodera S.
Proceedings of SPIE - The International Society for Optical Engineering 7271 2009年6月
記述言語：日本語 掲載種別：研究論文（学術雑誌） 出版者・発行元：Proceedings of SPIE - The International Society for Optical Engineering
We realized a laser-plasma EUV target, which satisfied the high EUV CE and the debris suppression simultaneously by using low-concentration liquid jet/droplet targets containing tin oxides and chlorides. Plasma regulation by double pulse irradiation improved the EUV CE. In terms of the debris emissions, we reduced the amount of the deposited tin oxide by applying in situ heat and high-energy photons onto a witness plate. These active debris suppression resulted in the decrease of the deposition rate and deoxidation of the debris, respectively. The use of tin chloride liquid target also realized a well-balanced debris behavior, where deposited debris was cleaned by chlorine atoms or ions, resulting in an approximately zero deposition rate. ©2009 SPIE.
DOI： 10.1117/12.813479
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Harmonic Generation in VUV Spectral Region Driven by a NIR Ti:Sapphire Laser in Rare Gases（共著）
M. Katto, K. Oda, M. Kaku, S. Kubodera, A. Yokotani, N. Miyanaga and K. Mima
Proceeding of SPIE, XVII International Symposium on Gas Flow and Chemical Lasers & High Power Lasers 7131 713118-1 - 713118-5 2009年6月
記述言語：英語 掲載種別：研究論文（国際会議プロシーディングス）
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EUV and debris characteristics of a laser-plasma tin-dioxide colloidal target（共著）
Shoichi Kubodera, Masanori Kaku, Shunsuke Touge, and Masahito Katto
Proceeding of SPIE, XVII International Symposium on Gas Flow and Chemical Lasers & High Power Lasers 7131 71311O-1 - 71311O-7 2009年6月
記述言語：英語 掲載種別：研究論文（国際会議プロシーディングス）
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OFI Argon Excimer Amplifier for Intense Subpicosecond VUV Pulse Generation（共著）
Masanori Kaku, Shoichi Kubodera, Kazuyoshi Oda, Masahito Katto, Atsushi Yokotani, Noriaki Miyanaga, and Kunioki Mima
Proceeding of SPIE, XVII International Symposium on Gas Flow and Chemical Lasers & High Power Lasers 7131 71311C-1 - 71311C-6 2009年6月
記述言語：英語 掲載種別：研究論文（国際会議プロシーディングス）
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OFI rare-gas excimer amplifier for high-intensity VUV pulse generation（共著）
Masahito Katto, Masanori Kaku, Kazuyoshi Oda, Tadashi Kamikihara, Atsushi Yokotani, Shoichi Kubodera Noriaki Miyanaga, and Kunioki Mima
Proceedings of SPIE, High Energy/Average Power Lasers and Intense Beam Applications III 7196 71930L-1 - L-8 2009年1月
記述言語：英語 掲載種別：研究論文（国際会議プロシーディングス）
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紫外・真空紫外光源の開発と光プロセスへの応用（共著）
甲藤正人，小田一義，上木原忠，和佐本真、高野智也、亀山晃弘、加来昌典，窪寺昌一，横谷篤至，宮永憲明，三間國興
レーザー学会第381回研究会報告「短波長光の発生とその応用」 RTM-08-43 5 - 10 2008年12月
記述言語：日本語 掲載種別：研究論文（その他学術会議資料等）
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EUV and debris characteristics of a laser-plasma tin dioxide nano-particle colloidal jet target
Kaku M., Suetake S., Senba Y., Katto M., Kubodera S.
Proceedings of SPIE - The International Society for Optical Engineering 6921 2008年12月
記述言語：英語 掲載種別：研究論文（国際会議プロシーディングス） 出版者・発行元：Proceedings of SPIE - The International Society for Optical Engineering
Debris characteristics and its reduction have been investigated for a laser-produced plasma (LPP) extreme ultraviolet (EUV) source using a colloidal jet target containing tin dioxide nano-particles. Dominant deposited debris on a witness plate was found to have a form of oxidized tin (SnOx) originated from nano-particles. Quantitative debris amounts were determined by total laser energy irradiated onto a target, not by laser irradiation modes, such as single or double pulse irradiation. In-situ low-temperature (100 °C) heating of a plate was effective to reduce the deposited debris amount, since colloidal debris was easily vaporized by the heat. Another approach to remove the deposited debris was roomtemperature photon processing using incoherent vacuum ultraviolet (VUV) emission at 126 nm. X-ray photoelectron spectroscopy (XPS) analysis has shown that the deposited SnOx debris layer was deoxidized by the 126 nm VUV photon energy.
DOI： 10.1117/12.771542
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Nano-particles of hydroxyapatite formed by underwater laser ablation method
Katto M., Kuroe Y., Kaku M., Kubodera S., Yokotani A., Katayama H., Nakayama T.
ICALEO 2008 - 27th International Congress on Applications of Lasers and Electro-Optics, Congress Proceedings 65 - 67 2008年12月
記述言語：英語 掲載種別：研究論文（国際会議プロシーディングス） 出版者・発行元：ICALEO 2008 - 27th International Congress on Applications of Lasers and Electro-Optics, Congress Proceedings
Hydroxyapatite (HAp) is a biocompatibility material. We have successfully obtained the nano-particles of hydroxyapatite by the underwater laser ablation. A sintered HAp ceramics target was made of commercially available HAp powder and it was placed in the purified water. The focused KrF excimer laser outputs were irradiated on the target surface at the fluence from 7 J/cm2 to 23 J/cm2 at the repetition rate of 100 Hz. We found that the amount of the particles increased in proportional to the laser fluence. However, the rate of content of sub-micron particles was became larger at the lower laser fluence. The particles made by 7J/cm2 laser ablation were dispersing in the water for 12 hours after stopping the laser irradiation.
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Auto-cleaning of deposited tin debris in a laser-produced plasma extreme ultraviolet source by using a liquid jet target containing tin chloride（共著） 査読あり
M. Kaku, S. Suetake, Y. Senba, M. Katto, S. Kubodera
Applied Physics B 93 361 - 364 2008年10月
記述言語：英語 掲載種別：研究論文（学術雑誌）
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Study of refractive index change in Ge-doped fibers with vacuum ultraviolet light irradiation 査読あり
Maezono Y., Iwasa Y., Wasamoto M., Yamamoto I., Katto M., Yokotani A.
Japanese Journal of Applied Physics 47 ( 9 PART 1 ) 7266 - 7268 2008年9月
記述言語：英語 掲載種別：研究論文（学術雑誌） 出版者・発行元：Japanese Journal of Applied Physics
We determined that refractive index change of Ge-doped silica can be induced by vacuum ultraviolet (VUV) light irradiation from Xe 2*, Kr2*, and Ar2* excimer lamps using fabricated fiber Bragg grating (FBG) in the core of the hydrogen-loaded fiber as the material. It was found that irradiation with light from Xe2* and Kr2* excimer lamps can change the refractive index in the core and irradiation with light from Ar 2* excimer lamps cannot. The change in refractive index under 146 nm light irradiation was greater than that under 172 nm light irradiation. The change in refractive index induced by irradiation with VUV light can be maintained up to approximately 130°C. © 2008 The Japan Society of Applied Physics.
DOI： 10.1143/JJAP.47.7266
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高機能性光源によるマテリアルプロセッシング（共著）
亀山 晃弘，和佐本 真，福永 出，岡崎 裕太郎，黒江 康博，高野 智也，若松 利享，甲藤 正人，横谷 篤至
レーザー学会第378回研究会報告「レーザー応用」 RTM-08-35 33 - 38 2008年9月
記述言語：日本語 掲載種別：研究論文（学術雑誌）
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Development of Intense Vacuum Ultraviolet Laser Systemfor Precise and Microscopic Processing（共著）
M. Katto, A. Yokotani, M. Kaku, K. Oda, S. Kubodera, N. Miyanaga and K. Mima
Proceedings of LPM 2008 #8-16 2008年9月
記述言語：英語 掲載種別：研究論文（国際会議プロシーディングス）
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Deposited debris characteristics and its reduction of a laser-produced plasma extreme ultraviolet source using a colloidal tin dioxide jet target（共著） 査読あり
Masanori Kaku, Sumihiro Suetake, Yusuke Senba, Shoichi Kubodera, Masahito Katto, and Takeshi Higashiguchi
Appllied Physics Letter 92 181503 2008年5月
記述言語：英語 掲載種別：研究論文（学術雑誌）
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高輝度真空紫外コヒーレント光源の開発（共著）
甲藤正人，小田一義，谷口雄太，加来昌典，横谷篤至，窪寺昌一，宮永憲明，三間國興
レーザー学会第368回研究会報告「短波長光の発生とその応用」 RTM-07-47 13 - 18 2007年12月
記述言語：日本語 掲載種別：研究論文（学術雑誌）
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Kaku M., Suetake S., Senba Y., Sato Y., Katto M., Kubodera S.
Pacific Rim Conference on Lasers and Electro-Optics, CLEO - Technical Digest 2007年12月
記述言語：日本語 掲載種別：研究論文（学術雑誌） 出版者・発行元：Pacific Rim Conference on Lasers and Electro-Optics, CLEO - Technical Digest
Characteristics of emitted particles from a laser-produced tin plasma using a colloidal tin dioxide nano-particle jet target were investigated. By using double laser pulses, the EUV conversion efficiency at 13.5 nm and the ion energy were simultaneously regulated. Deposited amount of tin oxide was not well controlled, however.
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Kaku M., Katto M., Kubodera S.
26th International Congress on Applications of Lasers and Electro-Optics, ICALEO 2007 - Congress Proceedings 2007年12月
記述言語：英語 掲載種別：研究論文（国際会議プロシーディングス） 出版者・発行元：26th International Congress on Applications of Lasers and Electro-Optics, ICALEO 2007 - Congress Proceedings
We investigated the effective technique for debris suppression of a laser-produced tin plasma using a colloidal tin dioxide jet target, as well as the EUV emission and debris characteristics of the target. By using double pulse laser irradiation with an optimum delay of 100 ns, the EUV conversion efficiency of 1.2% at 13.5 nm was observed. The peak energy and intensity of ionic debris were simultaneously reduced by the double laser pulse irradiation. The peak kinetic energy of the singly-ionized tin ion was reduced from 9 to 3 keV, when an expanding low-density preplasma was produced. The dominant debris from a laser-produced tin plasma, which was deposited on a witness plate, was found to be oxidized tin (SnOx). By heating a witness plate at 100 °C, the deposited debris amount decreased to approximately one third.
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OFI vacuum ultraviolet rare-gas excimer amplifier for subpicosecond VUV pulse amplification
Kaku M., Taniguchi Y., Hosotani A., Katto M., Yokotani A., Miyanaga N., Mima K., Kubodera S.
Pacific Rim Conference on Lasers and Electro-Optics, CLEO - Technical Digest 2007年12月
記述言語：英語 掲載種別：研究論文（研究会，シンポジウム資料等） 出版者・発行元：Pacific Rim Conference on Lasers and Electro-Optics, CLEO - Technical Digest
We evaluated amplification characteristics of the nanosecond vacuum ultraviolet argon excimer emission at 126 nm, whose kinetics was initiated by high-intensity femtosecond laser-produced electrons. Subpicosecond 126 nm emissions were produced simultaneously as a result of the nonlinear wavelength conversion, which will be amplified in the amplifier.
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Generation of intense vacuum ultraviolet radiations for advanced materials processing
Katto M., Yokotani A., Kubodera S., Kaku M., Hosotani A., Miyanaga N., Mima K.
26th International Congress on Applications of Lasers and Electro-Optics, ICALEO 2007 - Congress Proceedings 2007年12月
記述言語：英語 掲載種別：研究論文（国際会議プロシーディングス） 出版者・発行元：26th International Congress on Applications of Lasers and Electro-Optics, ICALEO 2007 - Congress Proceedings
We have been developing high intensity vacuum ultraviolet (VUV) laser system for advanced applications such as micro and precise processing and photochemical reactions. We propose and construct a new VUV laser system to generate an output energy of sub mJ with a pulse width of subpicosecond at the wavelength of 126nm. A seed pulse was generated in Xe as the 7th harmonics of a 882 nm Ti:sapphire laser, and the Ar2* amplifier media were generated in an optical-field-induced ionization Ar plasma produced by another 785 nm Ti:sapphire laser. The VUV radiation should be further amplified in a discharge-pumped Ar2* amplifier, which is under construction.
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Damage threshold of acrylic polymer jackets surrounded with optical fiber by UV laser
Maezono Y., Yousuke I., Kurosawa K., Katto M., Yokotani A.
Proceedings of SPIE - The International Society for Optical Engineering 6346 PART 2 2007年11月
記述言語：日本語 掲載種別：研究論文（学術雑誌） 出版者・発行元：Proceedings of SPIE - The International Society for Optical Engineering
Fabrication technique of fiber Bragg gratings (FBG) sensors, which is used the measurement of distortions of large scale architectural structures, requires a skillful technique, and consequently the costing becomes a problem. The fabrication technique without removing a polymer jacket can realize much easier fabrication and the cheaper cost. We have investigated the laser damage threshold of jackets in order to realize such a fabrication technique. The 3rd and the 4th harmonics of repetitive Nd:YAG laser pulse were used as light sources. An optical fiber coated untinged polymer jackets is used as a sample. The numbers of the shots against the same sample position was varied from 1 to 1200. As a result, damage thresholds at the shot number of 1200 were 6.9 J/cm 2 and 0.9 J/cm 2 for the wavelength of 355 nm and 266 nm, respectively. These values are corresponding to intensity of 1.3 MW/cm 2 and 0.3 MW/cm 2 , respectively. It is considered that the fabrication of FBG, which need a typical intensity of ∼kW/cm 2 , without removing the jacket should be possible by controlling the laser intensity between this level and the threshold.
DOI： 10.1117/12.739105
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Enhancement of extreme ultraviolet emission from a lithium plasma by use of dual laser pulses
Higashiguchi T., Kawasaki K., Senba Y., Suetake S., Katto M., Kubodera S.
Proceedings of SPIE - The International Society for Optical Engineering 6346 PART 2 2007年11月
記述言語：英語 掲載種別：研究論文（国際会議プロシーディングス） 出版者・発行元：Proceedings of SPIE - The International Society for Optical Engineering
We demonstrated enhancement of extreme ultraviolet (EUV) emission at 13.5 nm from a lithium plasma by use of dual laser pulses. A single laser pulse produced a lithium plasma condition for the EUV emission far beyond its optimum. Utilization of dual laser pulses, however, enhanced the EUV emission energy, and its maximum in-band EUV conversion efficiency (CE) in a measured solid angle was observed to be 2% at a delay time between 20 and 50 ns.
DOI： 10.1117/12.739115