The X-ray optical system in the wavelength range 1-300Å has made great progress owing to the technological development to fabricate X-ray optical elements such as multilayer reflectors and Fresnel zone plates. We present the X-ray characteristics of reflectors and detectors used for the grazing and normal incidence imaging optical systems such as X-ray telescope and microscope. Multilayer reflectors are versatile X-ray optical elements in constructing an X-ray reflecting optical system. A charge coupled device (CCD) is a promising X-ray detector for a highly sensitive X-ray imager with the energy discriminating capability.

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Polarization maintaining optical fibers currently receive a great interest in a number of sensor applications and coherent optical communication systems. Several different types of high-birefringent fibers produced by a variety of fabrication techniques are now available. Optical fiber components using them are also useful for making stable, compact and flexible fiber interferometers.
This paper reviews polarization maintaining optical fibers and their applications. In particular, recent interests in this field, such as single polarization fibers, polarization maintaining couplers and high-birefringent fibers with small diameters, are described.

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Fundamental studies on power transmission by using laser beam have been performed. The experimental results on a plasma direct converter (PDC) from laser energy to electricity are reported. We found that the conversion efficiency of laser energy to plasma varies with target materials and reaches the highest value of 70% for a NaCl target, and the conversion efficiency from energy of expanding plasma to electricity shows no variation with target materials. It is found that the conversion efficiency from laser energy to electricity is about 16% when a NaCl target is used.

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The generation of two-color 16-μm pulses by four-wave Raman mixing of TEA-CO₂lasers in para-H₂ was studied. The equations based on combination of four-wave mixing and stimulated Raman scattering were solved numerically, under the assumption of focused Gaussian beams with pump power depletion. The prediction of the model was experimentally verified with a couple of pulses from independent TEA-CO₂ lasers. Even a weak CO₂ laser whose power is not intense enough to induce effective Raman conversion by itself was efficiently converted to the Stokes pulse by the Raman mixing. The influence of beam crossing in a multiple-pass cell and transient response of a medium on the conversion process are also discussed.

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The electron quenching rate of KrF* in an electron beam pumped laser has been studied by accurately measuring the saturation intensity in a mixture of Ar/Kr/F₂=94/6/0.284. The input intensity of the measurements was widely varied from 100 W cm^-2 (small signal region) to 100 MW cm^-2 (absorption dominant region) in order to separate laser parameters which are small signal gain coefficient, absorption coefficient, and saturation intensity from the measured net gain coefficients. The gas pressure and the pump rate were varied in the range of 0.5 to 2.5 atm and 0.3 to 1.4 MW cm^-3, respectively. The electron quenching rate constant of 4.5×10^-7 cm3s^-1 was obtained from the pressure and the pump rate dependence of the KrF* saturation intensity with the temperature dependence of the rate gas 3-body quenching rate as a function of gas temperature to the -3rd power. The small signal gain coefficients calculated with the determined quenching rate constants shows excellent agreement with the measurements.

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Chip breaking during a finish boring process has previously been a problematic procedure due to a lack of suitable automatic chip breaking methods. This paper presents the novel and automatic chip breaking method that utilizes a YAG laser together with an optical fiber. Preliminary experiments with sample model chips showed that a YAG laser of a CW oscillation mode could cut the model chips for wider ranges of width and thickness than that of a Q-switched mode. Succeeding experiments on an actual turning process revealed that a focused laser beam of more than 10⁴ W/cm² fully covering the positional fluctuation of generating chips could cut chips satisfactorily. These experimental results were used in the design of a new tool holder with a YAG laser machining optics for finish boring. The tool holder exhibited an excellent performance under the conditions: a machining speed of 60m/min, a depth of cut of 0.05-0.1mm and a feed rate of 0.08-0.2mm/rev. The laser power used was 150 W.

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The TEA CO₂ laser-induced infrared multiphoton dissociation (IRMPD) of CTF₃ diluted in a large excess of a CHF₃ buffer gas cooled at -78 °Cwas studied as a function of laser fluence and gas pressure. The dissociation rate for CTF₃ increased with an increase in pressure in the region below 45 Torr owing to collisional relaxation of rotational bottle-necking, while it decreased above 45 Torr owing to collisional de-excitation. An energy-grained master equation (EGME) incorporating these pressure effects was used to simulate the experimental results on the CTF₃ dissociation. The EGME was numerically solved from trajectory calculations based on a stochastic method. We found that the EGME successfully predicted the pressure dependence of the IRMPD of CTF₃ over a wide range of experimental parameters.

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A practical dye laser system producing high-repetition rate/ (1kHz) amplified tunable/ (585-624nm) femtosecond/ (500fs) pulses and a compression to 29fs are described. The system consists of a hybridly mode-locked dye oscillator and a dye amplifier pumped by a frequency-doubled CW mode-locked Nd: YAG oscillator and regenerative amplifier output. The frequency tunable output pulses of 500fs duration and 500kW peak power are further compressed to 29fs by using a fiber grating compressor.

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