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Volume 35, Issue 3
Displaying 1-9 of 9 articles from this issue
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Shoichi KUBODERA2007 Volume 35 Issue 3 Pages 135
Published: March 15, 2007
Released on J-STAGE: March 26, 2014
JOURNAL FREE ACCESSDownload PDF (184K) -
Yasuo NABEKAWA2007 Volume 35 Issue 3 Pages 136-141
Published: March 15, 2007
Released on J-STAGE: March 26, 2014
JOURNAL FREE ACCESSIt is well known that a titanium doped sapphire (Ti: sapphire) crystal exhibits outstanding features as a laser material. We can easily handle the Ti: sapphire because it is highly stable in humidity, properly obtain high gain for the amplification due to the adequate emission crosssection, and also utilize it in a high-average powered amplifier because it can carry a heavy thermal load due to the high thermal conductivity. The most distinct feature of Ti: sapphire, however, is the broadest gain bandwidth of all the solid laser materials, which can serve the sufficiently broad spectrum to generate sub-10-femtosecond optical pulses. In this review, I introduce how we can generate high-intensity ultrashort pulses from the Ti: sapphire laser with ultrafast optical elements in a mod-locked oscillator and a chirped pulse amplification system, of which pulse duration comes down to sub-10-femtosecond regime.View full abstractDownload PDF (1244K) -
Shinji KIMURA, Takao IZAWA2007 Volume 35 Issue 3 Pages 142-147
Published: March 15, 2007
Released on J-STAGE: March 26, 2014
JOURNAL FREE ACCESSThis paper provides a review of the dielectric multilayer mirrors (DMM) for high power lasers and their applications. The laser damage resistance of DMM is one of the limiting factors for the development of high power laser applications, including material processing, scientific research and medical equipment. DMM have superior properties such as high resistance to laser damage, low optical losses and long-term stability, and are most suitable for high power laser applications. The laser damage resistance of DMM depends not only on coating materials, but also on the design and manufacturing processes. The properties concerning laser damage of DMM are introduced with some specific examples.View full abstractDownload PDF (8050K) -
Hiroshi KOMORI, Akira SUMITANI, Akira ENDO2007 Volume 35 Issue 3 Pages 148-153
Published: March 15, 2007
Released on J-STAGE: March 26, 2014
JOURNAL FREE ACCESSThe current status of the laser produced plasma light source development for EUV lithography is presented. Our key technology is based on an RF-excited CO2 driver laser combined with a Sn droplet target, because this approach enables cost-effective high-conversion efficiency. The RF-excited CO2 laser has a MOPA (master oscillator power amplifier) configuration. It currently generates an average output power of 2.6kW at 130kHz repetition rate. Due to negligible wavefront distortion of the laser beam during amplification, a laser focus of 100μm (FWHM) has been obtained. The Sn target and magnetic ion mitigation development as well as an evaluation of the collector mirror lifetime are presented.View full abstractDownload PDF (5889K) -
Hisataka TAKENAKA2007 Volume 35 Issue 3 Pages 154-161
Published: March 15, 2007
Released on J-STAGE: March 26, 2014
JOURNAL FREE ACCESSThe cosiderable progress in the development of extreme ultraviolet (EUV) sources such as laser-produced plasma, discharge-produced plasma, high-harmonic generation, X-ray laser, Synchrotron radiation, X-ray free electron laser will create new scientific research field and new industrial technology field. These EUV sources research have also led to progress in the development of EUV optical devices such as multilayer mirrors. This paper reviews the briefly history and recent results of multilayer optics for EUV.View full abstractDownload PDF (12786K) -
Yasuhisa SANO, Hidekazu MIMURA, Kazuya YAMAMURA, Kazuto YAMAUCHI, Yuzo ...2007 Volume 35 Issue 3 Pages 162-167
Published: March 15, 2007
Released on J-STAGE: March 26, 2014
JOURNAL FREE ACCESSAn ultraprecise aspherical mirror, which is difficult to fabricate by conventional mechanical machining, is required for optics, particularly in the field of coherent hard X-rays or extreme-ultraviolet lithography. In this review, we introduce new fabrication methods of elastic emission machining (EEM) and plasma chemical vaporization machining (PCVM). They are noncontact machining methods using chemical reactions and enable ultraprecise numerically controlled figuring by dwell time control. We also introduce ultraprecise aspheric ellipsoid mirrors for focusing hard X-rays fabricated using PCVM and EEM with a new figure testing method, were found to achieve nearly diffraction-limited focusing performance.View full abstractDownload PDF (9198K) -
Takeshi HIGASHIGUCHI, Shoichi KUBODERA2007 Volume 35 Issue 3 Pages 168-172
Published: March 15, 2007
Released on J-STAGE: March 26, 2014
JOURNAL FREE ACCESSWe report on a low-debris, efficient extreme ultraviolet (EUV) source by use of a liquid micro-target containing low-concentration tin oxide nano-particles. Conversion efficiency from a laser pulse energy to an in-band EUV energy (2% bandwidth (BW) and 2πIsr solid angle) depended on various experimental parameters, such as tin oxide concentration, laser intensity, and pulse separation time between dual laser pulses. By using a low concentration (6%) colloidal target together with dual laser pulses under the optimum separation time, we observed the EUV conversion efficiency of 1.2% with undetectable debris.View full abstractDownload PDF (7961K) -
Koichi WAKE, Hiroki OHKAWA, Shigeru YAMAGUCHI, Masamori ENDO, Kenzo NA ...2007 Volume 35 Issue 3 Pages 173-179
Published: March 15, 2007
Released on J-STAGE: March 26, 2014
JOURNAL FREE ACCESSWe described the demonstration of real-time NH3 detection with simulated flue gas conditions containing H2O and CO2 using direct laser absorption spectrometry. The most appropriate absorption lines at 3.03 and 1.54μm were carefully selected from the HITRAN database and the absorption spectral atlas of NH3 absorption in the 1.5μm region, and measurement sensitivity was compared in detail for absorption intensity and spectral interference associated with pressure broadening. Rapid NH3 detection with total measurement response time less than 10 seconds was achieved completely interference free from H2O and CO2 absorption spectra resulting in minimum detectable concentration of 0.7 ppm at 6510.986cm-1 and 2ppm at 3295.388cm-1 at an elevated gas temperature of 400 K.View full abstractDownload PDF (1402K) -
Sayaka OHMORI, Shiho HAKOMORI, Tsubasa TSUKAHARA, Tsunenori ARAI2007 Volume 35 Issue 3 Pages 180-186
Published: March 15, 2007
Released on J-STAGE: March 26, 2014
JOURNAL FREE ACCESSTalaporfin sodium mediated photosensitization effects induced by pulsed (FWHM: 8.7ns, 40Hz) or continuous wave (CW) irradiation were investigated in serum containing solution, in vitro, and in vivo. The singlet oxygen luminescence in the solution under the pulsed irradiation was significantly reduced to about 40% of the CW irradiation at the fluence rate of 200mW/cm2. The oxygen consumption in the solution and the photocytotoxicity against macrophage-like cells under pulsed irradiation was significantly decreased when the fluence rate increased from 20 to 400mW/cm2, while the these fluence rate dependences were minor under CW irradiation. The obtained fluence rate dependences of the singlet oxygen luminescence, oxygen consumption, and photocytotoxicity were consistently correlated to each other. The pulsed irradiation PDT on the rat subcutaneous prostate tumor treated at 400mW/cm2 and 100J/cm2 irradiation demonstrated the superficial tumor preservation. This preservation could not be explained the irradiation condition dependence of the obtained photocytotoxicity in vitro.View full abstractDownload PDF (9472K)
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