Hitachi Metals, Ltd.

Hitachi, Ltd.

Masayoshi Sato

Satoshi Makio

Yasunori Furukawa

Tsuyoshi Miyai

Kenichi Onda

Kohei Ito

Hiroshi Fukui

Hiroshi Kimura

Akihiko Kanouda

Norikazu Tokunaga

Katsunori Hayashi

Hisao Amano

Fumio Nitanda

Hideaki Horie

Hisao Kurosawa

Hironari Matsumoto

Hidenobu Ishida

Kenchi Ito

Kimio Tatsuno

Tetsuo Andou

Yasuo Matsuda

Kazumi Kawamoto

Shin Kimura

Shinji Yamada

Osamu Komoda

Kouzou Watanabe

Akio Miyamoto

Shuji Musha

Toru Abe

Hiroshi Momiji

Sten Helmfrid

Yasuo Abe

In a second harmonic, single-mode laser having a resonator including a Cr-doped fluoride laser crystal, first and second wavelength-selecting elements and a nonlinear optical crystal between a pair of laser mirrors, a wavelength-selecting width of the first wavelength-selecting element is {fraction (1/30)} or less of that of the second wavelength-selecting element, the first wavelength-selecting element is provided with a reflection coating having a reflectivity of 10-30% to the oscillated laser beam, such that the wavelength selection width of the first wavelength-selecting element is 0.02-0.03 nm, a wavelength interval in the oscillation wavelength range of the first wavelength-selecting element is 0.8-1.3 nm, and a wavelength selection width of the second wavelength-selecting element is 1.0-1.6 nm.

Second harmonic, single-mode laser

The free spectral range dependent on the length of an oscillator is put in a relation of integral times with respect to the free spectral range dependent on the length of at least a nonlinear optical crystal or a wavelength selection SHG output element. Thereby, reduced noise in the output of a second-harmonic generator is intended.

Reduced-noise second-harmonic generator and laser application device

A second harmonic generator comprising a semiconductor laser as an excitation light source and a resonator having a solid laser crystal excited by the excitation light source, a control element for controlling the wavelength of a first oscillation wave generated from the solid laser crystal and a nonlinear crystal for wavelength converting the first oscillation wave as a fundamental wave into a second harmonic wave as a second oscillation wave, wherein the components of the resonator are arranged in the order of a first laser mirror, solid laser crystal, wavelength control element, nonlinear crystal and second laser mirror from the input side of the excitation light.

Second harmonic generator and laser applied units

There is disclosed a harmonic modulation device of waveguide type including a semiconductor laser, a waveguide for generating a nonlinear optical harmonic of the semiconductor laser by keeping phase matching, means for leading an optical beam of the semiconductor laser to the waveguide, electrodes disposed on the waveguide, and means for modulating a refractive index of the waveguide electro-optically to modulate a phase matching condition and thereby modulate an intensity of the harmonic.

Short-wavelength laser light source

A laser having, a resonator structure including a wavelength variable laser crystal containing a fluoride and an optical part for controlling the wavelength of radiation from the laser crystal, a device to excite the laser crystal, a device for detect reflected light from the optical part as a sample beam, and a device to stabilize the output of a laser beam from the resonator structure based on the sample beam.

Laser and laser applied units

The invention relates to a power supply system having plural converters connected in parallel. The current of each of the plural converters is detected and each of the converters is controlled so as to match each of the converters to a maximum current value from among the detected current values. In the parallel converters, when one or more converter fails, having an output current of zero, the remaining converters are each partially charged equally to maintain the load current. Since a common bus is arranged between plural converters and plural loads, it is possible to carry out a redundant operation having a high reliability. Since a stable output can be obtained without being affected by the failed converter, a power supply system having the redundancy and the high reliability can be attained.

Power supply system for supplying electric power to a load through

A second harmonic generating apparatus including a semiconductor laser serving as a pumping source, a resonator structure for oscillating a first radiation wave generated by LiSAF (Cr:LiSrAlF.sub.6 : Lithium strontium aluminum fluoride with chromium added) crystal which is a solid-state laser crystal which is excited by the pumping source, a control element for controlling the wavelength of the first oscillation wave, and a nonlinear crystal for performing wavelength conversion into second harmonic which is a second oscillation wave, with the first oscillation wave serving as a fundamental wave, the nonlinear crystal being provided in the resonator. A higher efficiency and reliability of the second harmonic generating apparatus is achieved.

Second harmonic generating apparatus and apparatus employing laser

A parallelized power supply system including a plurality of switching power supplies each having a circuit for limiting rush current generated when a main switch is turned on. This system can be installed in an apparatus which requires the functions such as power uninterrupted operation and live wire insertion/dismount. Each switching power supply has another power supply for driving the rush current limiter circuit and a relay circuit for supplying relay driving current and making a connection of relay contacts after a predetermined time lapse after the operation start of the switching power supply. An a.c. power is supplied via the relay contacts to each switching power supply. The relay driving time set in the rush current limiter circuit is different for each switching power supply. Accordingly, concentration and excess of rush current when the relay is driven can be suppressed, and sparks at contact pins of a connector to be otherwise generated when the switching power supply is mounted on the connector, can be eliminated so that radiation noises and connector breakage can be avoided. Each of the switching power supplies connected in parallel has a current detecting resistor connected between the low voltage side of a load and the low voltage side of a voltage regulator d.c. output, and at least one operational amplifier for detecting a change in the d.c. output, the negative power supply terminal of the operational amplifier being connected to the current detecting resistor at its one end on the load side.

Parallelized power supply system providing uninterrupted operation

A laser apparatus including a laser crystal composed of a fluoride which contains chromium (Cr), a resonator which includes the laser crystal, a means for exciting the laser crystal, a first laser beam produced from light which is emitted from the laser crystal and oscillated in the laser resonator, and at least one optical component which is inserted in said resonator; wherein an aperture in the resonator is substantially five or more times the diameter of the first laser beam. A small, low-power SHG laser light source is achieved.

Laser apparatus and apparatus employing laser

0.1% or more of Mg by weight is added to lithium tantalate monocrystal materials wherein the amount of Fe is restricted to 10 ppm by weight or less to improve light transmittance in the short wavelength range of blue light and to shift the fundamental absorption edge to the shorter wavelength.

Lithium tantalate monocrystal, monocrystal substrate, and photo element

In growing an oxide single crystal such as a garnet single crystal or ferrite single crystal by the liquid epitaxial process, the Bridgman process or the like, the melting-out of a platinum or platinum-based alloy-made crucible holding a melt for growing the crystal therefrom is prevented by bringing an electrode in contact with the melt or dipping the electrode into the melt in oxygen, air or an inert gas, applying electric current through the melt between the electrode and the metallic container and controlling the current so as to keep it at nearly zero.

Method of producing single crystal and apparatus therefor

A power source having a first rectifier, a transformer having a primary coil and a secondary coil, switching elements having one end thereof connected to one of the terminals of the primary coil, a capacitor connected between other ends of the switching elements, diodes respectively connected between the terminals of the primary coil and the other ends of the switching elements, a choke coil for supplying the input DC voltage from the first rectifier directly to one of the terminals of the primary coil, and a second rectifier for supplying an output DC voltage to a load by rectifying the output AC voltage from the secondary coil.

Power source for supplying DC voltage by converting AC voltage from AC

A harmonics generation element which comprises a nonlinear optical element having single-crystals of lithium niobate containing magnesium of less than 5 atomic per cent. The nonlinear optical element has 3 ppm or less of impurity Fe and is configured so that a primary laser beam is made incident into the nonlinear optical element and a secondary output light having a wavelength of higher-order harmonics is emitted therefrom.

Harmonics generation element

A switching power supply using a step-up transformer whose impedance viewed from its primary side is different from the impedance viewed from its secondary side whereby the inductance of its primary and secondary windings are settable independently of each other.

Switching power supply

A semiconductor switching device includes a row of a plurality of switching elements connected in series. The input terminal of the input-nearest switching element and the output terminal of the output-nearest switching element are connected with the input terminal and output terminal of the semiconductor switching device, respectively. A control signal is applied to the control terminal of the output-nearest switching element. The semiconductor switching device comprises a first plurality of capacitive elements each of which is connected between the output terminal of the output-nearer switching element and the control terminal of the input-nearer switching element of the adjacent switching elements among the switching element row; and a second capacitive element connected between the output terminal and input terminal of the input-nearest switching element. At least the switching elements (S.sub.2 -S.sub.n) have insulating gates, respectively.

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Fukaya, Japan

Masayoshi Sato