All issues
Volume 36, Issue 9
Displaying 1-11 of 11 articles from this issue
- |<
- <
- 1
- >
- >|
-
Yasukazu IZAWA2008 Volume 36 Issue 9 Pages 529
Published: September 15, 2008
Released on J-STAGE: March 26, 2014
JOURNAL FREE ACCESSDownload PDF (196K) -
Noriaki MIYANAGA2008 Volume 36 Issue 9 Pages 530-537
Published: September 15, 2008
Released on J-STAGE: March 26, 2014
JOURNAL FREE ACCESSHigh-power laser is a typical multi-purpose technology that can be applicable to many fields including the basic science, the biomedical science and the metrology, inspection and fabrication in the material science and nanotechnology. This paper reviews high-power-laser produced radiation sources and applications of XUV-rays, energetic ions and neutrons. In addition the relevant world trend of next generation high-power lasers is reviewed on E23, ELI and HiPER-Euro programs.View full abstractDownload PDF (17659K) -
Benefits of Cooling and Recent DevelopmentShigeki TOKITA2008 Volume 36 Issue 9 Pages 538-543
Published: September 15, 2008
Released on J-STAGE: March 26, 2014
JOURNAL FREE ACCESSThe average power and the beam quality in solid-state lasers are limited by thermally induced effects such as thermal distortion, birefringence, or stress fracture in the laser medium. As one of the approaches to push beyond the power limitation, operating the laser medium at cryogenic temperatures has recently been demonstrated in various solid-state lasers. This approach takes advantage of significant improvement of the material's thermal properties at low temperatures such as higher thermal conductivity, lower thermo-optic coefficient (dn/dT), and lower thermal expansion. In the case of Yb-doped lasers, the cryo-cooling provides urther advantages. In cryogenic temperatures, the Yb-doped lasers become the four-level lasers, and consequently the laser threshold is greatly reduced. In addition, the emission cross section increases because of fluorescence line narrowing.View full abstractDownload PDF (1231K) -
Takagimi YANAGITANI, Hideki YAGI2008 Volume 36 Issue 9 Pages 544-548
Published: September 15, 2008
Released on J-STAGE: March 26, 2014
JOURNAL FREE ACCESSRecent great progress of ceramic manufacturing technology enabled transparent ceramics to be used as an optical material. The laser crystal can now also beapplied to ceramics. Ceramic laser material that has proper microstructure has several advantages compared with the single-crystal, such as larger aperture, mass production, higher optical homogeneity and so on. These advantages are suitable for the high power laser material. In this paper, we describe the manufacturing technique and the future of the ceramic laser material. We also introduce the development situation of a Solid State Heat Capacity Laser (SSHCL), which is one of the high power laser research programs, by using ceramic laser material.View full abstractDownload PDF (14458K) -
Junji KAWANAKA, Akira YOSHIDA, Ryo YASUHARA, Toshiyuki KAWASHIMA, Hiro ...2008 Volume 36 Issue 9 Pages 549-554
Published: September 15, 2008
Released on J-STAGE: March 26, 2014
JOURNAL FREE ACCESS“GENBU” -laser has been proposed to advance high power laser technologies at the next generation for not only inertial fusion driver but also many industrial applications. “GENBU” -laser is a combination of two systems, a main laser and an OPCPA laser to achieve kilo-joules pulse energy and ultra-high peak power over peta-watts. The pico-seconds main laser has been conceptually designed as a diode-pumped solid-state laser with chirped pulse amplification. A high pulse energy of 1kJ at 100Hz repetition rate is achieved by using new technologies of cryogenic Yb: YAG ceramics and large aperture active-mirror. “GENBU-Kid” -laser with 1 J, 100Hz is under construction to demonstrate the technologies in small scale.View full abstractDownload PDF (5071K) -
Koichi YAMAKAWA, Makoto AOYAMA, Yutaka AKAHANE, Kanade OGAWA, Koichi T ...2008 Volume 36 Issue 9 Pages 555-561
Published: September 15, 2008
Released on J-STAGE: March 26, 2014
JOURNAL FREE ACCESSWe review progress in the generation of ultrahigh-intensity optical pulses in a few-cycle regime. A design of a Generation of ENergetic Beam Ultimate (GENBU) laser based on optical parametric chirped-pulse amplification, which will be produced a peak power of up to 6-PW with a variable pulse durations ranging from 5-fs to 8-ps is described. Ultra-broadband optical parametric chirped-pulse amplification pumped by a picosecond laser pulse delivered from a diode-pumped, cryogenically-cooled Yb: YLF chirped-pulse amplification laser is also reported.View full abstractDownload PDF (1647K) -
Rüdiger BROCKMANN, David HAVRILLA, Koji WAKABAYASHI2008 Volume 36 Issue 9 Pages 562-565
Published: September 15, 2008
Released on J-STAGE: March 26, 2014
JOURNAL FREE ACCESSLaser welding has become one of the fastest growing areas for industrial laser applications. The increasing cost effectiveness of the laser process is enabled by the development of new highly efficient laser sources, such as the Disk laser, coupled with decreasing cost per Watt. We introduced the Disk laser several years ago, and today it has become the most reliable laser tool on the market. The excellent beam quality and output powers of up to 10kW enable its application in the automotive industry as well as in the range of thick plate welding, such as heavy construction and ship building. This serves as an overview of the most recent developments on our Disk laser and its industrial applications like cutting, welding, remote welding and hybrid welding, too. The future prospects regarding increased power and even further improved productivity and economics are presented.View full abstractDownload PDF (8921K) -
Hidetsugu YOSHIDA, Muneyuki NAGASAWA, Hajime OKADA, Hisanori FUJITA, M ...2008 Volume 36 Issue 9 Pages 566-572
Published: September 15, 2008
Released on J-STAGE: March 26, 2014
JOURNAL FREE ACCESSHeavy fluorocarbons and perfluoropolyether liquids are ideal media for high power stimulated Brillouin scattering experiments from ultraviolet to infrared laser. Stimulated Brillouin scattering (SBS) reflectivity and threshold of new SBS liquids were measured systematically at four wavelengths (1064,532,355 and 266nm). Fluorinert FC-72,-75,-77 and Galden HT-70,-135 exhibits high reflectivity of over 90% and excellent fidelity in phase conjugation for over 100mJ, 10ns optical pulse at 1064,532, and 355nm. Among them, FC-77 and HT-70 were found to be good candidates to replace FC-72,-75 liquids which previously were known to be a good SBS media up to now. Heavy fluorocarbons and perfluoropolyether liquids are most promising as a phase conjugate SBS mirror for all solid-state high-energy lasers because of its high damage threshold and low absorbance.View full abstractDownload PDF (1136K) -
Hidetsugu YOSHIDA, Norihiro TAKEUCHI, Hajime OKADA, Hisanori FUJITA, M ...2008 Volume 36 Issue 9 Pages 573-578
Published: September 15, 2008
Released on J-STAGE: March 26, 2014
JOURNAL FREE ACCESSWe have successfully demonstrated the compensation of thermal lens effect in Nd: YAG laser rods regardless of pumping condition by inserting a solid-state self-adaptive CE (Compensating Element), having negative dn/dT property between two Nd: YAG rods. Several organic resins and a LiF crystal of higher negative dn/dT which have high damage threshold and low absorbance are very useful to compensate thermal effects in the amplifier. The results revealed that the use of several organic resins resulted in the complete reduction of the thermal lens effect by an order of magnitude. This compensation scheme is an ultimate method because of its dynamic compensation feature independent of the pumping power level.View full abstractDownload PDF (11980K) -
Fumio MATSUDA, Taku OKAJIMA, Jyunnpei SUGIURA, Isao CHOUNANN, Hideo KI ...2008 Volume 36 Issue 9 Pages 579-583
Published: September 15, 2008
Released on J-STAGE: March 26, 2014
JOURNAL FREE ACCESSTwo methods of displacement measurement of object with diffusing surface have been developed already.One is by speckle pattern interferometry method with wavelength order accuracy and a half wavelength measurement area, and another is by triangle method with micrometer order accuracy and a millimeter measurement range. We propose a method of complex displacement measurement by using the speckle pattern interferometry method and the triangle method. In both methods, measurement point on object surface is the same.In this paper, a calculation method used in the method of complex displacement measurement is described.The method make that displacement measurement of object with diffusing surface can be available with wavelength order accuracy and a millimeter measurement area.View full abstractDownload PDF (8039K) -
Hitoshi NAKANO, Akira OKAMOTO, Yasufumi FUJIMOTO, Makoto YAMADA2008 Volume 36 Issue 9 Pages 584-586
Published: September 15, 2008
Released on J-STAGE: March 26, 2014
JOURNAL FREE ACCESSA fast high-voltage switch has been developed by using insulated gate bipolar transistors (IGBTs). The IGBTsare connected in series to achieve a high voltage rating. An avalanche transistor is used as the gate driver. Thefast pulse generated by the avalanche transistor quickly charges the large input capacitance of the IGBT, resulting in a switch out of a fast high-voltage pulse. An output amplitude of 2.5kV with a rise time of 8ns hasbeen achieved; this characteristic is applicable to operating a plasma generator, a high-voltage switch for adischarge-pumped laser, and a Pockels cell driverView full abstractDownload PDF (360K)
- |<
- <
- 1
- >
- >|