Anritsu Corporation

Nippon Telegraph and Telephone Corporation

Takeshi Tsukamoto

Takao Tanimoto

Masaya Nanami

Hiroshi Goto

Hidetoshi Miyao

Youichi Tamura

Yasutaka Ichihashi

Toshiyuki Suzuki

Takamasa Imai

A laser absorption spectroscopy type gas detection device is provided in which a light source device emits a laser beam containing a light component having a wavelength corresponding to an absorption spectrum of gas to be detected. A concave mirror has a reflecting surface to reflect and condense the laser beam reflected by material body existing in an advancing direction of the laser beam. A light receiver is disposed at the condensing position by the concave mirror and outputs an electric signal for detecting whether the gas to be detected is present in a vicinity of the material body. An adjustment mechanism freely moves and adjusts a relative position of the concave mirror and the light receiver in accordance with a distance to the material body such that the light receiver is positioned at the condensing position.

Laser absorption spectral diffraction type gas detector and method for gas detection using laser absorption spectral diffraction

A gas detecting apparatus includes a gas cell, a laser source, a light diffuser and a photodetector. The gas cell has a gas inlet hole for letting the target gas come inside and a gas discharge hole for discharging the target gas, and retains a target gas to be detected. The laser source emits coherent light into the gas cell in order to detect a concentration of the target gas. The light diffuser is disposed in the optical path of the coherent light output from the laser source to diffuse the coherent light, thereby eliminating coherence of the coherent light. The photodetector receives light diffused by the light diffuser.

Gas detecting apparatus using laser absorption spectroscopy

Light wavelength measuring apparatus including an interference

A system for measuring a chromatic dispersion of an optical fiber based on a baseband phase comparison method has an optical signal transmitter, a reference optical fiber, a measurement optical fiber, and an optical signal receiver. The transmitter has n light sources for selectively generating, as measurement optical signals, optical signals having wavelengths corresponding to n wavelength points to be measured. One of the n light sources also serves to generate a reference optical signal. The transmitter further has an optical switch. The optical switch has n optical signal inputs arranged in correspondence with the n light sources, a measurement optical signal output, and a reference optical signal output. The optical switch commonly outputs, to the measurement optical signal output, the measurement optical signal which is output from the designated one of the n light sources and is selectively input to the n optical signal inputs. A half mirror is provided for outputting the reference optical signal generated by one of the n light sources to the reference signal output. The optical signal receiver is coupled to the reference optical fiber and the measurement optical fiber, and receives the reference optical signal from the reference optical fiber and the measurement optical signal from the measurement optical fiber, respectively, for measuring chromatic dispersion. The receiver includes a plurality of programmable optical attenuators.

Chromatic dispersion measuring system for optical fibers

A system for measuring a chromatic dispersion of an optical fiber has a light signal transmitter and a light signal receiver. The transmitter has a modulation signal generating circuit for generating at least one modulation signal having a predetermined frequency, and synchronizing signal generating circuit for generating a synchronizing signal having a predetermined frequency. First adding circuit is provided for adding the synchronizing signal generated by the synchronizing signal generating circuit to the modulation signal generated by the modulation signal generatig circuit. The light signal receiver has first photoelectric converter for converting the reference optical signal into a reference electrical signal added with the synchronizing signal and second photoelectric converter for converting the measurement optical signal into a measurement electrical signal added with the synchronizing signal. The receiver also has a synchronizing signal regenerating circuit for generating a regenerated synchronizing signal at a predetermined timing, and local signal generating circuit for generating at least one local signal having a predetermined frequency. Second adding circuit is provided for adding the regenerated synchronizing signal to the local signal from the local signal generating circuit. Further, a timing signal obtaining circuit is provided for separating the synchronizing signal from the reference electrical signal added with the synchronizing signal from the first photoelectric converter to obtain a timing signal serving as the synchronizing signal, in order to provide the predetermined timing to the synchronizing signal regenerating means.

Growing community of inventors

Hadano, Japan

Takeshi Tsukamoto