Hitachi Cable, Inc.

Masaki Ogura

Juhyun Yu

Masahiko Kobayashi

Hidetaka Kawauchi

Akihiro Hiruta

An optical fiber temperature sensing device has a sensor body; a light source housed in the sensor body; a temperature measuring optical fiber disposed outside the sensor body and extended to a temperature measurement site, wherein, when a light is emitted from the light source into the temperature measuring optical fiber, Stokes light intensity and anti-Stokes light intensity of backscattered light generated in the temperature measuring optical fiber are detected to determine a temperature at the temperature measurement site; a reference temperature optical fiber disposed inside the sensor body; and a controller that is operable to control an output of the light source by monitoring Stokes light intensity and anti-Stokes light intensity of backscattered light generated in the reference temperature optical fiber.

Optical fiber temperature sensing device

An optical sensor has: a sensing portion having an optical fiber to be disposed at a measurement point of temperature, distortion, pressure etc.; a light source to output a light to the sensing portion; and a photodetector to detect a backscattered light from the sensing portion. The sensing portion has a tape sheet and the optical fiber shaped into a corrugated form with a predetermined curvature. Alternatively, the sensing portion has a polymer optical waveguide with a core shaped into a corrugated form with a predetermined curvature.

Optical sensor, optical temperature-measuring device and measuring method using the optical sensor

An optical fiber temperature sensor has a sensing part composed of an optical fiber arranged at a temperature measurement point; a light source for injecting a light to the sensing part; a wavelength filter module for branching the Raman scattered light from the back scattered light generated at the sensing part; photoelectric detectors for detecting the Raman scattered light and a signal processing circuit for processing the electric signals from the photoelectric detectors, wherein the light source is a semiconductor laser having a wavelength bandwidth of 0.78 &#x3bc;m; the wavelength filter module has a longer wavelength side band pass filter for transmitting the Stokes light and a shorter wavelength side band pass filter for transmitting the anti-Stokes light; and the longer wavelength side band pass filter and the shorter wavelength side band pass filter do not allow the light having the wavelength band of the semiconductor laser to be transmitted.

Optical fiber temperature sensor

A signal converter for converting a digital input signal to an optical modulation signal includes a pilot signal-superimposing circuit which superimposes a pilot signal on a bias control signal, a monitor circuit for providing a monitor signal by receiving a part of the optical modulation signal supplied from the optical modulator, a first feedback system for providing an amplitude control signal to control an amplitude of the digital input signal through a frequency deviation signal obtained from the monitor signal, and a second feedback system for providing the bias control the bias signal through a multiplying frequency deviation signal obtained from the monitor signal.

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Hitachi, Japan

Masaki Ogura