Mitsubishi Denki Kabushiki Kaisha

Hitachi, Ltd.

Mitsubishi Electric Corporation

Rohm Co., Ltd.

Hamamatsu-photonics K.k.

Osaka University

Kyoto University

Hitachi Mito Engineering Co., Ltd.

Tetsuo Kojima

Susumu Konno

Junichi Nishimae

Shuichi Fujikawa

Koji Yasui

Kiyoshi Nakata

Toshiaki Okuyama

Tomotaka Katsura

Yuichiro Nozaki

Masafumi Makino

Masashi Yoshimura

Takatomo Sasaki

Seiji Ishida

Akira Horie

Takashi Yamamoto

Akira Ishimori

Kuniaki Iwashiro

Takeshi Shinomiya

Tetsu Sugiura

Hiroyuki Suzuki

Susumu Noda

Yoshitaka Iwaji

Yukio Sato

Tatsuya Yamamoto

Yusuke Mori

Eiichi Toyota

Yoko Inoue

Shinsuke Yura

Motomi Shimada

Masato Kawasaki

Kazuki Kuba

Atsuhiro Sono

Kazutoshi Morikawa

Toyoki Asada

Toshihiko Sekizawa

Masaomi Konishide

Shuichi Tachihara

Yasuhiko Kono

Eiichi Tanaka

Toshifumi Sakai

Muneyuki Nishioka

Takafumi Kawai

Seiji Ishda

Yongqiang Xia

Takashi Ogawa

Takehiro Kawamoto

Kazufumi Muraoka

A laser module includes: a photonic crystal surface-emitting laser element; a collimating lens array for producing a parallel optical beam; a condenser lens for condensing the optical beam; and an optical fiber which receives the optical beam on one end and transmits the optical beam to the outside. In the collimating lens array, an aperture portion corresponding to a collimating lens allows passage of the optical beam with an energy of not less than 94.0% and not more than 99.5% with respect to 100% of the energy of the optical beam incident on the collimating lens array.

Laser module and laser processing apparatus

In order to cause the residual magnetic flux in an induction motor to decay in a short time without an excessive current flow, an induction motor control apparatus continues an operation in which an inverter apparatus is caused to output a zero voltage to the induction motor for a predetermined time before deactivating an operation of the inverter apparatus.

Control method for induction motor

A DC power supply including a resonant circuit on a secondary side of a transformer suppresses a surge voltage during power recovery of diodes constituting a rectifier circuit, correctly estimates a load current from a secondary current of the transformer, and adjusts supplied power when a load is light. The DC power supply includes a DC voltage source, a converter, a transformer, a rectifier circuit, a resonant circuit composed of a resonant switch and a resonant capacitor, a filter reactor, a filter capacitor, a snubber diode, a snubber capacitor, a load, first and second voltage sensors, a current sensor, and a controller for controlling gate pulses of semiconductor devices constituting a converter and the resonant switch and a signal for adjusting operation timings of A/D converters converting the signals of these sensors.

DC power supply including resonant circuit for reducing switching losses

Semiconductor element groups constituting a unit are mounted on a cooler heat receiving parton the same plane and are adapted to radiate heat by self-cooling or cooling by wind. First and fourth semiconductor elements Q, Qare arranged on the lower side of the cooler heat receiving part, second and third semiconductor elements Q, Qare arranged in the middle, a first diode Dand a second diode Dare arranged on the upper side, the first and second semiconductor elements Q, Q, as well as the third and fourth semiconductor elements Q, Qare each arranged in positions opposite to each other in a horizontal direction with respect to a centerline of a cooler in a vertical direction.

Electric power conversion device

In a DC power supply in which a DC power source and a transformer are connected via a power conversion circuit and a secondary winding of the transformer is connected to a load via a rectifier diode bridge and a filter circuit to supply power to the load, a resonance reactor is provided on an output side of the transformer, a resonant switch circuit including a parallel circuit of a diode and a semiconductor switch and a resonant capacitor is connected in parallel to the rectifier diode bridge and a snubber circuit including a snubber capacitor, a snubber diode and a diode for discharge is connected to a serial resonant circuit including the resonance reactor and the resonant capacitor in the resonant switch circuit to absorb a surge voltage.

DC power supply including arrangement to reduce switching loss and a snubber circuit to suppress surge voltages

An optical wavelength conversion element includes a cesium-lithium-borate crystal processed into a 10-mm long optical element cut in an orientation that allows a fourth harmonic of a Nd:YAG laser to be generated. A transmittance (Ta) at 3589 cmin an infrared transmission spectrum of the optical element is used as an index that indicates a content of water impurities in the crystal and is independent of a polarization direction. An actual measurement of the transmittance Ta is at least 1%, without taking into account loss at an optically polished surface of the crystal. A wavelength conversion device, a ultraviolet laser irradiation apparatus, a laser processing system, and a method of manufacturing an optical wavelength conversion element are also described.

Optical wavelength conversion element having a cesium-lithium-borate crystal

Two convex lenses (), each of which has a focal length 'f', and a 90 degree polarization rotator () are interposed between solid-state laser elements () of a symmetrical resonator having the two solid-state laser elements (); a space between the two lenses () is made shorter than 2f; and distances between the respective lenses () and centers of their adjacent solid-state laser elements () are set substantially to 'f', to thus achieve a solid-state laser capable of stably performing high power transverse single mode oscillation desirably having power of 100 W or more. There is acquired a wavelength conversion laser that is further provided with a Q switch () and a polarization element () and that causes an output fundamental wave laser beam to enter nonlinear elements () so as to undergo wavelength conversion, thereby producing a high power harmonic laser beam having a high frequency of; desirably, about 100 kHz.

Solid state laser and wavelength conversion laser

A diode laser pumped solid-state laser amplifier capable of homogenizing the distribution of heat dissipation levels on a section of a solid-state laser rod and not causing a bifocal phenomenon, and a diode laser pumped solid-state laser using the diode laser pumped solid-state laser amplifier. A diode laser pumped solid-state laser amplifier includes a solid-state laser rod having an optical axis along which a laser beam propagates and includes an active medium therein and a plurality of pumping sources having optical axes that run on a plane orthogonal to the axial core of the solid-state laser rod and are separated by a given distance from the axial core of the solid-state laser rod. When pumping light rays are projected on a plane orthogonal to the axial core of the solid-state laser rod, the plurality of pumping sources are located at equiangular intervals with respect to the axial core of the solid-state laser rod.

Diode laser pumped solid state laser amplifier and diode laser pumped solid state laser

In the case where, e.g., because of provision of a high-gain and high-energy Q-switched laser oscillator in a laser system in a MOPA configuration, the duration &#x3c4;z from the time point when oscillation-stage Q switches (and) start the gate ON to the time point when a pulse laser beam () starts to grow is shorter than the fall time &#x3c4;f of amplification-stage Q switches (,, and), by implementing control in such a way that the gate-ON timing of the oscillation-stage Q switches (and) lag behind the gate-ON timing of the amplification-stage Q switches (,, and) by a predetermined time, the loss in the pulse laser beam () at the amplification-stage Q switches (,, and) can be prevented, while the gain deterioration due to a spontaneously amplified ray () produced in the amplification stage is being suppressed. Therefore, a high-energy pulse laser beam can efficiently be obtained.

Laser system

A simple and high-reliability constitution provides a solid-state laser system that allows a high-output, long-pulse-width laser beam to be obtained. A solid-state laser system that includes a solid-state laser medium, a light sourcefor pumping the solid-state laser medium, two reflecting mirrorsandfor flanking the solid-state laser medium, thereby constituting a laser resonator, is constituted in such a manner that a virtual-mirror planeis defined in the space between the solid-state laser mediumand the reflecting mirror; a lensis provided between the virtual-mirror planeand the reflecting mirror; and, by means of the forward and backward paths along the route from the virtual-mirror plane to the reflecting mirror by way of the lens, the virtual-mirror plane in the forward path and the virtual-mirror plane in the backward path are made in an optically conjugated relationship with each other.

Solid-state laser system

A fundamental laser beam is wavelength converted through nonlinear optical crystals by traveling in one direction, sequentially through two nonlinear optical crystals arranged in series. A wavelength-converted laser beam is generated and includes wavelength-converted laser beams having polarized directions differing from each other by angles in a range from 45&#xb0; to 90&#xb0;. The two nonlinear optical crystals have crystal orientation axes differing by 45&#xb0; to 90&#xb0; when viewed along the optical axis of the laser beam.

Wavelength conversion method, wavelength conversion laser, and laser beam machining apparatus

Laser equipment in which pumping every dependence of output beam diameter and beam wavefront curvature is reduced. The total pumping energy of at least one of laser active media disposed beyond terminal laser beam waists, among beam waists, is approximately one-half of the total pumping energy of laser active media disposed between two adjacent beam waists.

Pumping method for laser equipment

A wavelength conversion apparatus in which output direction of a wavelength-converted laser beam, having a wavelength converted by a nonlinear optical crystal and emitted through an output-window, can be brought close to the direction of optical axis of the laser beam passing through the nonlinear optical crystal. In addition, axial deviation of the wavelength-converted laser beam converted by the nonlinear optical crystal and emitted through an output-window, can be reduced when the position of the nonlinear optical crystal is moved. The output facet of the nonlinear optical crystal is inclined at Brewster's angle with respect to the wavelength-converted laser beam. An output-window of a case containing the nonlinear optical crystal has a prism form in which the distance between a laser beam input facet and a laser beam output facet of the output-window is reduced along a direction in which the wavelength-converted laser beam, emitted from the nonlinear optical crystal, inclines.

Wavelength conversion apparatus

In a wavelength converting method, an ambient that is in contact with a surface of a non-linear optical crystal from which wavelength-converted light is outputted is a gas that is lower in content of nitrogen than air. A wavelength converting device includes a device for controlling the ambient in contact with a surface of the non-linear optical crystal from which the wavelength-converted light is outputted so the ambient is lower in nitrogen than air. A laser machining device includes the wavelength converting device.

Wavelength conversion method, wavelength conversion device, and laser beam machine

Filter capacitor voltage &ldquo;Ecf &rdquo; is detected and then after d-axis voltage correction value &ldquo;dvd&rdquo;, q-axis voltage correction value &ldquo;dvq&rdquo;, q-axis current correction value &ldquo;diq&rdquo;, and frequency correction value &ldquo;d&ohgr; &rdquo; have been computed from the AC components of &ldquo;Ecf &rdquo; and the results have been added to the corresponding d-axis voltage command, q-axis voltage command, q-axis current, and frequency command, the DC current of the power converter is controlled. Thus, the AC components included in the DC current are offset and the AC components are suppressed effectively.

Control apparatus for power converter

Growing community of inventors

Tokyo, Japan

Tetsuo Kojima