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Volume 30, Issue 9
Displaying 1-10 of 10 articles from this issue
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Special Issue on Generation of Ultrashort EUV and X-ray and Their Application
Special Issue
Laser Reviews
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Shuntaro WATANABE2002 Volume 30 Issue 9 Pages 502
Published: September 15, 2002
Released on J-STAGE: October 21, 2009
JOURNAL FREE ACCESSDownload PDF (123K) -
Taro SEKIKAWA, Tomotaka KATSURA, Shuntaro WATANABE2002 Volume 30 Issue 9 Pages 503-507
Published: September 15, 2002
Released on J-STAGE: October 21, 2009
JOURNAL FREE ACCESSThe temporal profile and phase of the fifth harmonic of a Ti:sapphire laser were fully characterized by two-photon ionization (TPI) frequency-resolved optical gating (FROG) technique for the first time. The fifth harmonic was found to have negative chirp and the pulse compression was demonstrated. The negative chirp is well explained by using a zero-range potential model. TPI FROG is scalable to XUV and soft x-ray regions by using currently available light sources, making it possible to measure the pulse duration and phase of VUV, XUV, and soft x-ray pulses.View full abstractDownload PDF (626K) -
Hidetoshi NAKANO, Tadashi NISHIKAWA, Katsuya OGURI, Naoshi UESUGI2002 Volume 30 Issue 9 Pages 508-512
Published: September 15, 2002
Released on J-STAGE: October 21, 2009
JOURNAL FREE ACCESSHigh-density plasmas created near a solid surface by a femtosecond laser pulse emit ultrashort x-ray pulses that are synchronized with the laser pulse. We achieved more than 30-fold enhancement of the soft x-ray emission by fabricating an array of nanoholes on an alumina surface. We measured the duration of the soft x-ray emitted from the laser plasma by the cross-correlation method using an optical field-induced ionization process in Kr gas. Utilizing a 10-ps soft x-ray pulse, we measured the time-resolved absorption of optically excited silicon near its LII,III edge. We found that laser-pulse irradiation caused a more than 10 % increase in the soft x-ray absorption near the edge, which recovered within 20 ps. We assume the origin of this absorption change to be the bandgap renormalization of Si. We also employed picosecond soft x-rays to measure the ablated particles in Al plasma created by a 100-fs laser pulse.View full abstractDownload PDF (733K) -
Kazutaka G. NAKAMURA, Yoichiro HIRONAKA, Ken-ichi KONDO2002 Volume 30 Issue 9 Pages 513-517
Published: September 15, 2002
Released on J-STAGE: October 21, 2009
JOURNAL FREE ACCESSGeneration of ultrashort hard X-ray pulses using laser-driven electron X-ray sources and picosecond time-resolved X-ray diffraction measurements are reviewed. Hard X-ray pulses are characterized by measurements of energy spectrum and pulse duration. Picosecond lattice dynamics of laser-irradiated silicon crystal measured by time-resolved X-ray diffraction is described.View full abstractDownload PDF (741K) -
Masafumi YOROZU, Fumio SAKAI, Akira ENDO2002 Volume 30 Issue 9 Pages 518-524
Published: September 15, 2002
Released on J-STAGE: October 21, 2009
JOURNAL FREE ACCESSThis paper describes a femtosecond X-ray source using a laser-Compton scheme, which is an interaction between a relativistic electron beam and a high-intensity laser beam. The system is constructed of a picosecond electron beam source based on a linac with a photocathode RF gun and a 1-TW Ti:sapphire laser. Experimental studies and new applications of the laser Compton X-ray beam are summarized.View full abstractDownload PDF (705K) -
Yoshihito TANAKA, Toru HARA, Hideo KITAMURA, Tetsuya ISHIKAWA2002 Volume 30 Issue 9 Pages 525-530
Published: September 15, 2002
Released on J-STAGE: October 21, 2009
JOURNAL FREE ACCESSThe combination of an intense pulsed laser and the SPring-8 X-ray synchrotron radiation (SR) pulses has enabled us to make time-resolved X-ray diffraction measurements on picosecond time scale. The laser-SR synchronization technique needed for the time-resolved measurements and the performance obtained at SPring-8, are described. By using the synchronization system, the laser-induced crystal lattice expansion with a response time of a few hundred picoseconds was observed. Application of the laser-induced lattice expansion to a fast X-ray shutter is also described.View full abstractDownload PDF (675K)
Laser Originals
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Takahiro INOUE, Shuji MIYAMOTO, Sho AMANO, Takayasu MOCHIZUKI, Mitsuya ...2002 Volume 30 Issue 9 Pages 531-537
Published: September 15, 2002
Released on J-STAGE: October 21, 2009
JOURNAL FREE ACCESSA femtosecond synchrotron radiation pulse train can be extracted from an electron storage ring by interaction between an ultrashort laser pulse and an electron beam in an undulator. Generation system of a femtosecond soft x-ray pulse by the slicing technique was studied with numerical calculations for its performance, as applicable for the NewSUBARU synchrotron radiation facility at LASTI. The femtosecond electron pulse, that is energy-modulated with a Ti:sapphire laser at a pulse energy of 100 μJ, a pulse width of 150 fs, and repetition frequency of 20 kHz, can be sufficiently separated in a bending magnet. A femtosecond soft x-ray pulse (the critical photon energy of 0.69 keV and a pulse width of 250 fs) is obtained with a collimator (diameter of 800 μmφ), and it has an average brightness 3 × 106 photons/s/mm2/mrad2/0.1 %BW and an average photon flux 105 photons/s/0.1 %BW.View full abstractDownload PDF (690K) -
Riichi ONO, Tomosumi KAMIMURA, Satoru FUKUMOTO, Muneyuki NISHIOKA, Mas ...2002 Volume 30 Issue 9 Pages 538-541
Published: September 15, 2002
Released on J-STAGE: October 21, 2009
JOURNAL FREE ACCESSA nonlinear optical crystal CsLiB6O10 (CLBO) is suitable for high-power solid-state ultraviolet (UV) lasers. One of the factors limiting the increasing of UV power is the formation of laser-induced damage. To obtain high-quality CLBO, we have developed a new growth apparatus based on an effective solution stirring technique. The grown crystals have a higher bulk laser-induced damage threshold than that of conventional crystals. They also possess sufficient optical uniformity for practical use in industrial fields. Furthermore, these high-quality CLBO are clearly superior in terms of dislocation density, Vickers hardness, and self-heating by UV absorption. Using these crystals, 266-nm UV power of 20 W operating over 100 hours was achieved.View full abstractDownload PDF (509K)
Regular Papers
Laser Originals
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Noriko MOCHIZUKI-ODA, Yosky KATAOKA, Yilong CUI, Yasuhisa TAMURA, Hisa ...2002 Volume 30 Issue 9 Pages 542-545
Published: September 15, 2002
Released on J-STAGE: October 21, 2009
JOURNAL FREE ACCESSLow-power, near-infrared laser irradiation has been used to relieve patients of various kinds of pain, but the precise mechanisms of this biological action by a laser have not yet been clarified. To investigate the cellular mechanisms induced by a near-infrared laser on the nervous system, we examined the effect of 830-nm laser irradiation on the energy metabolism of the rat brain. A diode laser was applied for 15 min with irradiance of 4.8 W/cm2. Tissue ATP content of the irradiated area in the cerebral cortex was 19% higher than that of the non-treated area. Laser irradiation at another wavelength (652 nm) had no effect on ATP content. The temperature increase of the tissue during irradiation did not depend on the wavelength. These results suggest that the increase in tissue ATP content did not result from the thermal effect but from a specific effect of the laser operated at 830-nm wavelength.View full abstractDownload PDF (416K) -
Tetsuya TANIYAMA, Takahiko SHOUJI2002 Volume 30 Issue 9 Pages 546-550
Published: September 15, 2002
Released on J-STAGE: October 21, 2009
JOURNAL FREE ACCESSIrradiation of intensity modulated laser beam to a aluminum block induces the thermo elastic wave. We have studied to detect the defect and to evaluate its depth from the metal surface by measuring the phase of the induced thermo elastic wave with PZT attached at the back side of the aluminum block. We made it possible to detect the defect but could not evaluate its depth. In the present work, we have discussed the method to evaluate the depth of the defect in an aluminum specimen having a cylindrical hollow between 0.8 × 10-3 m and 2.0 × 10-3 m of diameter. The results have shown that both the diameter of the cylindrical hollows and its depth from the surface can be determined with the modulation frequency 12 kHz for the depth less than 1 × 10-3 m.View full abstractDownload PDF (792K)
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