Ando Electric Company

Other

Nippon Telegraph and Telephone Corporation

Akio Ichikawa

Shoichi Aoki

Fumio Akikuni

Eiichi Sano

Kenji Mogi

Eiji Yoshida

Toshiyuki Takeda

Masataka Nakazawa

Satoshi Matsuura

Yoshihiro Kumagai

Rikihiro Iida

Yuka Asahina

A position sensor for movable body, which detects a position of a movable body which moves in a reciprocal direction, comprises; at least two portions to be detected, which are provided on one side surface of the movable body with respect to a moving direction of the movable body, and at least two detectors for detecting the portions to be detected, wherein one portion to be detected is not arranged on a line parallel to the moving direction, on which the other portion is disposed, nor arranged on a line perpendicular to the moving direction, on which the other portion is disposed, one detector corresponding to the one portion is arranged so that when the one detector detects the one portion by moving the movable body in one direction, the other portion is moved in the one direction beyond the one detector, and the other detector corresponding to the other portion is arranged so that when the other detector detects the other portion by moving the movable body in the other direction, the one portion is moved in the other direction beyond the other detector.

Position sensor for movable body and optical interferometer

A DSP&num;B executes, prior to data conversion, interpolation (see FIG. ) in order to interpolate discrete spectra obtained via the FFT processing by a DSP&num;A . In the interpolation, the DSP&num;B executes two-point interpolation if the difference between two discrete spectrum data pieces F(j) and F(j&plus;1) is greater than a predetermined threshold &egr; and four-point interpolation if the difference is smaller than &egr;.

Data processor and data processing method for wavemeter

A chromatic dispersion distribution measurement apparatus, comprises: a chromatic dispersion value calculation unit for calculating a plurality of actual chromatic dispersion values in an optical device at a plurality of wavelengths; and a chromatic dispersion interpolation unit for interpolating an expected chromatic dispersion value between the actual chromatic dispersion values calculated by the chromatic dispersion value calculation unit, in order to obtain a chromatic dispersion distribution as a function of wavelength.

Chromatic dispersion distribution measurement apparatus and method for the same

A chromatic dispersion distribution measurement apparatus, comprises: a portion information obtaining unit for obtaining a portion information which specifies a portion of an optical device to be measured; a sign information obtaining unit for obtaining a sign information which indicates a correct sign to be marked on a chromatic dispersion value in the specified portion; and a sign converting unit for converting an initial sign marked on the chromatic dispersion value in the specified portion, into the correct sign in accordance with the sign information obtained by the sign information obtaining unit.

Chromatic dispersion distribution measurement apparatus, method and storage medium for the same

The CPU outputs to the delay circuit delay time setting signals for setting the delay time, based on input delay time data input from an external input device. The delay circuit re-sets the delay time via new delay setting signals input from the CPU and delays the trigger signals input from the trigger circuit based on the specified delay time and outputs the resulting signals to the clock generator The clock generator outputs new sample start signals to the A/D sampler at the input timing of the delayed trigger signals input from the delay circuit thus changing the sampling start timing of interference signals in the A/D sampler.

The DSP&num;A specifies a read address for reading digital interference signal data stored in the buffer to read the data, and executes the butterfly operation including a preset hamming windowing function coefficient to convert digital interference signal data to frequency data, then outputs the frequency data to the DSP&num;B

A chromatic dispersion distribution measurement apparatus for calculating a chromatic dispersion distribution in an optical communication path under test, includes an intensity ratio calculation unit for calculating an intensity ratio of a first light and a second light that are reflected from an optional position of the optical communication path under test and propagated to an incident end of the optical communication path under test by taking the same propagation time. A chromatic dispersion value calculation unit is provided for calculating a chromatic dispersion value in the optical communication path under test in accordance with the intensity ratio calculated by the intensity ratio calculation unit.

A chromatic dispersion distribution measurement apparatus, comprises: a power calculation unit for calculating a power value of an input light to be input into an optical device to be measured, in order to calculate a chromatic dispersion distribution in the optical device to be measured, in accordance with an output light power of an output light from the optical device to be measured as a function of a transmission distance along the optical device to be measured; and a control unit for controlling an input light power of the input light to the optical device to be measured in accordance with the power value of the input light which is calculated by the power calculation unit.

An optical part driving device for moving an optical part, comprises; a driving timing pulley, a pair of driven timing pulleys, a timing belt wound by the driving timing pulley and the driven timing pulleys and connected with the optical part between the pair of driven timing pulleys, and a pair of tension pulleys for tensing the timing belt on both sides of the driving timing pulley.

Optical part driving device incorporated into a detachable block and optical interferometer including same

An optical interferometer in which a reference light and a light to be measured interfere with each other includes a casing, a movable optical part which is movable with respect to the casing, a fixed optical part which is fixed to the casing, and an attachment emember for attaching the movable optical part to the casing and for removing the movable optical part form the casing.

Optical interferometer with a casing and an optical part that is movable with respect to the casing

The object of the present invention is to provide an optical pulse generator which very stably generates for a long period of time a high cycling frequency optical pulse chain. In order to obtain this object, in a ring type resonator R, the present invention provides an optical path length regulator 14 which performs high precision optical path length adjustment and an optical path length regulator 60 which performs wide range optical path length adjustment, and extracts a clock signal by converting an optical pulse emitted from the ring type resonator R to an electrical signal by a clock extractor 42, detects the frequency difference between a base frequency signal output form a synthesizer 52 by a frequency difference detector 50, and controls said optical path length regulator 14 and said optical path length regulator 60.

Optical pulse generator

According to the present invention, damage to a photo-detector disposed in clock signal extractor by means of an optical pulse having an optical power exceeding a rated value is prevented. A ring resonator generates a repetitive, high-frequency optical pulse. Optical branching circuit branches a portion of the optical pulse circulating through ring resonator, while optical branching circuit further branches a portion thereof to protective device. Pumping source generates an excitation light for exciting a rare-earth doped optical fiber. Optical multiplexer couples the optical pulse branched by optical branching circuit, and the excitation light. Upon excitation by means of the excitation light, rare-earth doped optical fiber amplifies and emits the incoming optical pulse. The optical power of the excitation light is adjusted such that the output of rare-earth doped optical fiber reaches a saturation power. Optical switch blocks the incoming optical pulse during the time period when pumping source is not emitting an excitation light, and during a fixed time period following the emission of the excitation light. In this manner, the entry of an excessively large optical pulse exceeding the saturation power into photo-detector at the time of starting up the power source is prevented. Optical attenuator attenuates the optical power of the optical pulse emitted from optical switch to an optical power which the photo-detector is capable of photo-detecting. Photo-detector converts the optical pulse emitted from protective device into an electronic signal; narrow band filter extracts a clock signal from the output of photo-detector; and electric amplifier amplifies the output of narrow band filter, and outputs a clock signal. Phase shifter adjusts the phase of this clock signal; electric amplifier amplifies the output of phase shifter, and outputs a clock signal to optical modulator. Optical modulator modulates the intensity of the light circulating through the ring resonator based on the clock signal, and generates an optical pulse.

An optical phase locked loop circuit, which controls so that the optical frequency of the light 19A generated by the slave laser 19 has the offsetting factor to the optical frequency of the coherent light 11A generated by the master laser 11, corresponding to the frequency of the signal 16A generated by the signal generator 16, is provided with a LPF 1, an optical power controller 2 and a variable optical attenuator 3. Upon detecting the phase difference caused by the difference frequency between the light 19A and the coherent light 11A, the output control light 3A is obtained by transmitting the output control light 20B through the variable optical attenuator 3. The signal 13B proportional to the optical power of the output control light 3A is extracted by the LPF 1. The optical power of the light 3A is stabilized by using the optical power controller 2 and the variable optical attenuator 3 in order to vary the optical power attenuation in the light 20B corresponding to the extracted signal 13B.

Optical phase locked loop circuit

A polarization is controlled by introducing a phase difference in an incident light at first, then introducing a phase difference by 45 degrees, and then the polarized light is rotated. The light is passed through an analyzer so arranged that the direction of the transmission axis of the analyzer does not coincide with the principal axes of the means for introducing the phase differences, thereby to convert the polarized condition into a light volume which is used to control the phase differences and the rotation.

Polarization control system

An optical fiber testing apparatus for testing an optical fiber as to presence and location of a fault such as breakage by inputting a pulsed coherent light beam to the optical fiber and synthesizing a return light beam reflected back from the optical fiber with a reference light beam having a frequency deviated from the pulsed light beam by a predetermined amount, wherein the synthesized waveform is detected through optical heterodyning. The electric signal obtained from the heterodyning detection is detected by an envelope detector, of which dynamic range is effectively virtually broadened by using correcting data prepared previously. The optical fiber test can be accomplished through a single measurement without involving expensiveness of hardware.

Growing community of inventors

Tokyo, Japan

Akio Ichikawa