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Journal Articles

Laminar and blazed type holographic gratings for a versatile soft X-ray spectrograph attached to an electron microscope and their evaluation in the 50-200 eV range

Imazono, Takashi; Koike, Masato; Kawachi, Tetsuya; Hasegawa, Noboru; Koeda, Masaru*; Nagano, Tetsuya*; Sasai, Hiroyuki*; Oue, Yuki*; Yonezawa, Zeno*; Kuramoto, Satoshi*; et al.

Applied Optics, 51(13), p.2351 - 2360, 2012/05

 Times Cited Count:11 Percentile:50.91(Optics)

Laminar and blazed types holographic varied-line-spacing spherical gratings for use in a versatile soft X-ray flat-field spectrograph attached to an electron microscope are designed, fabricated, and evaluated. The absolute diffraction efficiencies of laminar (or blazed) master and replica gratings at 86.00$$^circ$$ incidence evaluated by synchrotron radiation show over 5% (or 8%) in the 50-200 eV range with the maxima of 22% (or 26-27%). Also the resolving power evaluated by a laser produced plasma source is in excess of 700 at the energy near the ${it K}$ emission spectrum of lithium ($$sim$$55 eV) for all gratings. Moreover, the ${it K}$ emission spectrum of metallic Li with high spectral resolution is successfully observed with the spectrograph attached to a transmission electron microscope.

Journal Articles

High spatiotemporal-quality petawatt-class laser system

Kiriyama, Hiromitsu; Mori, Michiaki; Nakai, Yoshiki; Shimomura, Takuya; Sasao, Hajime; Tanaka, Momoko; Ochi, Yoshihiro; Tanoue, Manabu*; Okada, Hajime; Kondo, Shuji; et al.

Applied Optics, 49(11), p.2105 - 2115, 2010/04

 Times Cited Count:39 Percentile:84.5(Optics)

We have developed a femtosecond high intensity laser system, which combines both Ti:sapphire chirped-pulse amplification (CPA) and optical parametric chirped-pulse amplification (OPCPA) techniques, that produces more than 30-J broadband output energy, indicating the potential for achieving peak powers in excess of 500-TW. With a cleaned high-energy seeded OPCPA preamplifier as a front-end in the system, for the compressed pulse without pumping the final amplifier we found that the temporal contrast in this system exceeds 10$$^{10}$$ on the sub-nanosecond timescales, and is near 10$$^{12}$$ on the nanosecond timescale prior to the peak of the main femtosecond pulse. Using diffractive optical elements for beam homogenization of 100-J level high-energy Nd:glass green pump laser in a Ti:sapphire final amplifier, we have successfully generated broadband high-energy output with a near-perfect top-hat-like intensity distribution.

Journal Articles

Self-seeding of a pulsed double-grating Ti:sapphire laser oscillator

Tamura, Koji

Applied Optics, 47(10), p.1517 - 1521, 2008/04

 Times Cited Count:10 Percentile:47.74(Optics)

A self-seeded pulsed double-grating Ti:sapphire laser oscillator consisting of a grazing incidence cavity geometry with a pair of gratings and a standing-wave cavity was developed and was characterized. The narrow-linewidth single-longitudinal-mode (SLM) operation and the SLM scan were possible with considerably reduced lasing threshold by self-seeding desirable for its applications.

Journal Articles

Characterization of a high-brilliance soft X-ray laser at 13.9 nm by use of an oscillator-amplifier configuration

Nishikino, Masaharu; Hasegawa, Noboru; Kawachi, Tetsuya; Yamatani, Hiroshi; Sukegawa, Kota; Nagashima, Keisuke

Applied Optics, 47(8), p.1129 - 1134, 2008/03

 Times Cited Count:43 Percentile:86.69(Optics)

Journal Articles

Fabrication and evaluation of a wideband multilayer laminar-type holographic grating for use with a soft-X-ray flat-field spectrograph in the region of 1.7 keV

Imazono, Takashi; Ishino, Masahiko; Koike, Masato; Sasai, Hiroyuki*; Sano, Kazuo*

Applied Optics, 46(28), p.7054 - 7060, 2007/10

 Times Cited Count:18 Percentile:64.66(Optics)

A multilayer laminar-type holographic grating having an average groove density of 2400 lines/mm is designed and fabricated for use with a soft X-ray flat field spectrograph covering the 0.70-0.75 nm region. A varied-line-spaced grooves pattern is generated by the use of an aspheric wavefront recording system and laminar-type grooves are formed by a reactive ion-etching method. Mo/SiO$$_2$$ multilayers optimized for the emission lines of hafnium M, silicon K, and tungsten M are deposited on one of the three designated areas on the grating surface in tandem. The measured first-order diffraction efficiencies at the respective centers of the areas are 18$$sim$$20%. The flat field spectrograph equipped with the grating indicates a spectral line width of 8$$sim$$14 eV for the emission spectra generated from electron-impact X-ray sources.

Journal Articles

Single-longitudinal-mode scan of a pulsed double-grating Ti:sapphire oscillator

Tamura, Koji

Applied Optics, 46(23), p.5924 - 5927, 2007/08

 Times Cited Count:3 Percentile:19.99(Optics)

The method to scan grazing incidence laser oscillator was proposed with increased dispersion and mode stability keeping the longitudinal mode condition. By the rotation around arbitrary center and translation of cavity length, equations for dispersion and longitudinal mode can be satisfied using a simple mechanism, and enhanced tunability was obtained compared with interferometer type oscillator. It contributes to the laser material processing study with high selectivity.

Journal Articles

Development of a chirped pulse amplification laser with zigzag slab Nd:glass amplifiers dedicated to X-ray laser research

Ochi, Yoshihiro; Hasegawa, Noboru; Kawachi, Tetsuya; Nagashima, Keisuke

Applied Optics, 46(9), p.1500 - 1506, 2007/03

 Times Cited Count:34 Percentile:80.89(Optics)

A chirped pulse amplification laser with zigzag slab Nd:glass amplifiers dedicated to X-ray laser research is described. The laser provides a 1.6-ps duration pulse with $$sim$$7 J energy at repetition rate of 0.1 Hz. The amplification is made in two steps: first 10$$times$$10 mm$$^{2}$$ beam is amplified from $$sim$$mJ to $$sim$$J in the first amplifier with image-relayed multi-pass amplification. Then the laser light is expanded to be 10$$times$$90 mm$$^{2}$$ and amplified up to $$>$$10 J in the second amplifier. The gain-saturated Ni-like silver laser at a wavelength of 13.9 nm has been successfully produced by this laser system.

Journal Articles

Development of multilayer laminar-type diffraction gratings to achieve high diffraction efficiencies in the 1-8 keV energy region

Ishino, Masahiko; Heimann, P. A.*; Sasai, Hiroyuki*; Hatayama, Masatoshi*; Takenaka, Hisataka*; Sano, Kazuo*; Gullikson, E. M.*; Koike, Masato

Applied Optics, 45(26), p.6741 - 6745, 2006/09

 Times Cited Count:12 Percentile:48.04(Optics)

no abstracts in English

Journal Articles

Fabrication of multilayer mirrors consisting of oxide and nitride layers for continual use across the K-absorption edge of carbon

Ishino, Masahiko; Yoda, Osamu

Applied Optics, 43(9), p.1849 - 1855, 2004/03

 Times Cited Count:1 Percentile:8.71(Optics)

The development of multilayer mirrors for continual use around the K-absorption edge of carbon (4.4 nm) has been begun. Co$$_3$$O$$_4$$, SiO$$_2$$, and BN are found to be suitable for multilayer mirrors based on theoretical calculations for wavelengths around the carbon K-absorption edge region. X-ray reflectivity curves with Cu$$K$$$$_{alpha1}$$ X rays of the fabricated Co$$_3$$O$$_4$$/SiO$$_2$$ multilayers have sharp Bragg peaks and the layer structures evaluated from TEM observations are uniform. On the other hand, the Bragg peaks of Co$$_3$$O$$_4$$/BN multilayers split and aggregated Co$$_3$$O$$_4$$ is observed. To improve the Co$$_3$$O$$_4$$ layer structure, Cr$$_2$$O$$_3$$ was mixed into Co$$_3$$O$$_4$$. The mixed oxide layer structure in the Mix/BN multilayer (Mix = Co$$_3$$O$$_4$$ + Cr$$_2$$O$$_3$$) is relatively uniform and the Bragg peaks do not split.

Journal Articles

Development of a pumping laser system for X-ray laser research

Kawachi, Tetsuya; Kado, Masataka; Tanaka, Momoko; Hasegawa, Noboru; Nagashima, Keisuke; Sukegawa, Kota*; Lu, P.; Takahashi, Kenjiro; Namba, Shinichi; Koike, Masato; et al.

Applied Optics, 42(12), p.2198 - 2205, 2003/04

 Times Cited Count:27 Percentile:72.65(Optics)

no abstracts in English

Journal Articles

Grazing-incidence Monk-Gillieson monochromator based on surface normal rotation of a varied-line-spacing grating

Koike, Masato; Namioka, Takeshi*

Applied Optics, 41(1), p.245 - 257, 2002/01

 Times Cited Count:14 Percentile:54.75(Optics)

A plane grating monochromator having a simple wavelength scanning method requiring only a rotation of a grating about its normal was analyzed on the basis of the light path function. This scanning method has been known as surface normal rotation (SNR). A varied line spacing (VLS) plane grating was assumed to be illuminated by a convergent beam generated by a spherical mirror. We gave the analytical expressions for the grating equation, focal conditions, direction of dispersion, slant angle and length of astigmatic image, and a method to optimize the groove parameters of the VLS grating. The results of this analysis and the expected resolving power were evaluated by means of ray tracing for two model systems.

Journal Articles

Tunable continuous-wave Yb:YLF laser operation with a diode-pumped chirped-pulse amplification system

Kawanaka, Junji; Nishioka, Hajime*; Inoue, Norihiro*; Ueda, Kenichi*

Applied Optics, 40(21), p.3542 - 3546, 2001/07

 Times Cited Count:55 Percentile:89.23(Optics)

no abstracts in English

Journal Articles

Comparison of mechanically ruled versus holographically varied line-spacing gratings for a soft-X-ray flat-field spectrograph

Yamazaki, Takashi; Gullikson, E. M.*; Miyata, Noboru*; Koike, Masato; Harada, Yoshihisa*; Mrowka, S.*; Kleineberg, U.*; Underwood, J. H.*; Yanagihara, Mihiro*; Sano, Kazuo*

Applied Optics, 38(19), p.4001 - 4003, 1999/07

 Times Cited Count:22 Percentile:70.13(Optics)

no abstracts in English

Journal Articles

High-repetition rate 1-J green laser system

*; Kato, Masaaki; Matsuoka, Fumiaki*; Niwa, Yoshito*; Maruyama, Yoichiro; Matoba, Toru; Arisawa, Takashi

Applied Optics, 38(21), p.4548 - 4551, 1999/07

 Times Cited Count:8 Percentile:43.32(Optics)

no abstracts in English

Journal Articles

Direct bonding of Ti:sapphire laser crystals

Sugiyama, Akira; *; Sasuga, Tsuneo; Arisawa, Takashi; *

Applied Optics, 37(12), p.2407 - 2410, 1998/04

 Times Cited Count:29 Percentile:78.48(Optics)

no abstracts in English

Journal Articles

Characteristics of a dye laser amplifier transversely pumped by copper vapor lasers with a two-dimensional calculation model

Sugiyama, Akira; *; Kato, Masaaki; Maruyama, Yoichiro

Applied Optics, 36(24), p.5849 - 5854, 1997/08

 Times Cited Count:3 Percentile:23.22(Optics)

no abstracts in English

Journal Articles

Two-step selective photoionization of rubidium by using a Ti:sapphire laser

; Oba, Masaki; Arisawa, Takashi

Applied Optics, 32(6), p.987 - 991, 1993/02

 Times Cited Count:4 Percentile:32.71(Optics)

no abstracts in English

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