Nec Corporation

Mitsubishi Heavy Industries Limited

Mitsubishi Heavy Industries Automotive Thermal Systems Co., Ltd.

Yukio Michishita

Satoshi Ishii

Takaaki Ogata

Takashi Ishide

Koji Okimura

Yoshio Hashimoto

Yasumi Nagura

Michisuke Nayama

Makoto Takeuchi

Masao Watanabe

Hiroshi Ogawa

Takayuki Hagita

Kazuhide Watanabe

Hiroaki Murakami

Katsuhiro Fujita

Yasuhiro Aoki

Takayuki Kuwahara

Yoshiro Sato

Kenichi Yoneyama

Takashi Akaba

Nobuyuki Hori

Takahiro Ota

Tadashi Nagashima

Takaaki Kobayashi

Masafumi Hamasaki

Takaharu Maeguchi

Masaki Kawasaki

Katsusuke Shimizu

Yukihiro Kawai

Nariyasu Matsubara

A method for manufacturing a compressor scroll that appropriately impinges cavitation bubbles on target regions of a scroll. The method includes the step of water jet peening by jetting cavitation bubbles generated underwater by a water jet at a first side of an end plate (A) of the scroll (), with a center (P, P, P) of the cavitation bubbles being offset from a center (O) of the spiral shape of a wall portion (B) on the end plate (A) and the step portion (Aa) and the stepped portion (Ba) positioned at an outer peripheral portion of the cavitation bubbles (C).

Method and device for manufacturing compressor scrolls, compressor scroll, and scroll compressor

A plastically deformable almen strip is held under a predetermined underwater environment in which water jet peening is carried out, and a result of providing compressive residual stress in the water jet peening is confirmed by jetting water jet to the almen strip.

Water jet peening compressive residual stress test method, test device, and test facility

Terminal equipment of a wavelength division multiplexing optical transmission system is provided with a monitoring apparatus for monitoring optical transmission paths with an OTDR. For this monitoring, OTDR probe lights of different wavelengths are allocated to optical fibers and optical amplifier-repeaters, which are elements constituting the optical transmission paths. Further, different wavelengths are allocated to OTDR probe lights between the up link and the downlink. Such a wavelength as makes the wavelength dispersion over the optical transmission paths negative (usually the shorter wavelength side than the zero dispersion wavelength of the optical transmission paths) is allocated to the OTDR probe light for optical fiber monitoring, and a wavelength longer than 1550 nm is allocated to the OTDR probe light for optical amplifier-repeater monitoring.

Optical transmission path monitoring system, monitoring apparatus therefor and monitoring method therefor

In a 32-channel wavelength division multiplexing optical transmission system, for example, four optical transmitters are grouped in eight groups. Each group is provided with a control optical transmitter. The control light transmitter regulates the level of a control light so that the total level of light transmitted from the corresponding group is equal to the total level of four signal lights. An optical transmission line of the above-mentioned system is normally regulated beforehand so that the wavelength characteristic of the following signal lights is flat when light at the total level of thirty-two signal lights in a predetermined range of wavelengths is transmitted. Therefore, in the system according to the invention, independent of the number of signal lights, the receive level of a signal light is unchangeable.

Wavelength division multiplexing optical transmission method and system

A compensation scheme for an optical amplifier that reduces differences in gain observed at various wavelengths combines and controls characteristics of an automatic gain control circuit and variable gain equalizers. The peak gain wavelength typically observed in optical amplifiers is reduced by shifting the variable gain equalizer characteristic, which has a wavelength region of maximum gain loss. By combining the characteristics of the peak wavelength gain with the maximum wavelength loss according to the various elements, a smooth gain curve can be realized. A variable gain equalizer control circuit provides the required control, and can control multiple variable gain equalizers positioned in various numbers and locations with regard to an optical amplifier section.

Optical amplifier

A light amplifier is provided which is capable of maintaining the output light of excitation light sources at a constant level even when the light power input into the rare earth containing optical fiber fluctuates due to the tracking error of the excitation light source or due to the temperature characteristic or the polarization dependence of the excitation light multiplexer. The light passed through the rare earth containing optical fiber is extracted after being split by the splitting device 3, and output levels of the excitation light sources and are controlled by a control circuit in response to the levels of the extracted light. Consequently, the light output can be maintained at a constant level even when the excitation light power input into the optical fiber fluctuates due to the polarization dependence or the temperature characteristic of the light multiplexer for supplying the excitation light into the optical fiber.

A laser beam machining head includes a dividing optical system for dividing laser light into two separate laser beams, and providing spacing therebetween; a condensing optical system for condensing the separate laser beams into condensed laser light, and projecting it onto a cutting site of an object to be cut; and an inner assist gas nozzle placed between the separate laser beams, a width of an opening of a tip portion of the inner assist gas nozzle being nearly equal to a cutting width. Or the tip opening of the inner assist gas nozzle is slender; or its tip side is inclined, and the angle of inclination is variable; or the relative positions of the inner assist gas nozzle and a workpiece, or the relative positions of the focal position of the condensing optical system and the workpiece are variable independently; or an outer assist gas nozzle surrounding the separate laser beams is provided.

Laser beam machining head

In a laser beam machine head, when a filler wire and an optical axis of a laser beam are arranged coaxially, a convex roof mirror and a concave roof mirror are combined to divide the laser beam into two separate laser beams to that no laser beam is projected onto a filler wire feed pipe. Furthermore, the filler wire is fed from outside the laser beams to a condensing position via a filler wire guide in the spacing between the separate laser beams, or an electrode supported by a water flow pipe or an electrode holding pipe is brought close to the condensing position.

A signal conversion device comprises a light source for emitting continuous wave (CW) light at a predetermined wavelength &lgr;, an optical element having a saturable absorption function, and a wavelength demultiplexing circuit for separating signal light at a desired wavelength from signal light outputted from the optical element. A threshold value for optical transmission and absorption of the optical element having the saturable absorption area is set to a level such that applied signal light at a wavelength &lgr;s and the CW light outputted from the light source are absorbed at a light intensity level of either of the two lights, and are transmitted at a light intensity level of a total of the two lights.

Method and apparatus for wavelength conversion of signal light

An optical amplifier for wavelength multiplex transmission is capable of reducing the gain difference of each wavelength. A pumping light source generates pumping lights to excite an optical fiber for amplification for amplifying wavelength multiplexed optical signals, a wavelength optical multiplexer inserts these pumping lights to the optical fiber for amplification, an optical coupler branches the optical signals amplified by the optical fiber for amplification, and a wavelength separator separates the branched optical signals into ASE and signal lights. A photo receiver detects the strength of separated ASE, a photo detector detects the strength of signal light. A strength level comparator/pumping light source controller controls the output of the pumping light source, based on the strength detected by the photo detector so that the output level of the optical signal is set arbitrary. Therefore, by controlling the output level of the pumping light source, it is capable of setting the amplification factor of suitable gain flatness.

Optical amplifier for wavelength multiplex transmission

In an optical amplifying for amplifying an input wavelength multiplexed signal into an amplified output wavelength multiplexed signal, each of the input wavelength multiplexed signal and the amplified output wavelength multiplexed signal containing a plurality of optical component signals which have wavelengths different from one another, and each of which has an amplitude level, the optical amplifying apparatus comprises an optical amplifier for amplifying the input optical wavelength multiplexed signal into the amplified output wavelength multiplexed signal and an optical detecting circuit for individually detecting the amplitude level of at least one of the optical component signals.

Optical amplifying apparatus capable of detecting at least one of

An optical amplifier system includes a branching filter for branching into respective wavelengths a wavelength-multiplexed incident light having wavelengths .lambda..sub.1 to .lambda..sub.n, which is inputted from an input port. N optical amplifier sections respectively amplify the branched lights of respective wavelengths. An optical multiplexer multiplexes the amplified lights having the wavelengths .lambda..sub.1 to .lambda..sub.n before outputting the light to an output port. An output control circuit sets the output level of the optical amplifier section to an arbitrary value. With this composition, the present invention is capable of increasing the optical output level per wavelength, independently of the wavelength multiplex number n, when a light signal having n wavelengths is to be amplified.

Optical amplifier system generating high optical output level

Optical surge preventing systems and methods for rare earth-doped optical fiber amplifiers are disclosed. The systems are so arranged as to cause any signal existing in a doped fiber section so as not to over excite the rare earth elements in the doped fiber section. In one embodiment, a background signal light with such a wavelength as to cause induced emission in the doped fiber section is always coupled into the doped fiber section regardless of whether a message signal light exists or not. The background signal light may be generated by any suitable light source or a light spontaneously emitted from either end of the doped fiber section. In another embodiment, a dummy signal light is coupled into the doped fiber section if the level of the message signal light becomes less than a predetermined value. Coupling of the background signal light or the dummy signal light into the doped fiber section may be done from either of the message signal input and output sides.

Optical surge preventing method and system for use with or in a rare

At a transmission section, different frequencies ranging from f1 to fn corresponding to n channels are generated as channel information, respectively. The signal light (.lambda.1 to .lambda.n) of each channel is modulated at the corresponding frequency (f1 to fn) and multiplexed. At a reception section, in case of selecting the channel of the signal light .lambda.1, the wavelength selection characteristic of a filter is sweep controlled for detecting the frequency f1. The wavelength selection characteristic at the f1 detection is kept as the wavelength selection characteristic of the filter.

Wavelength division multiplexing optical transmission system and

In a data communication system, a circuit for regenerating an optical signal that is deteriorated during the course of transmission has an optical clock generator for generating an optical clock signal whose frequency is equal to the bit rate of an optical signal input to a preselected port thereof. The clock generator outputs the clock signal via the same port as the optical signal is input. The circuit is capable of regenerating the optical signal while efficiently separating the optical signal and clock signal respectively input to and output from the clock generator.

Growing community of inventors

Tokyo, Japan

Yukio Michishita