Optical fiber temperature distribution measurement device and method of measuring optical fiber temperature distribution

Patent metadata

Field	Value
Publication number	US-9689751-B2
Application number	US-201414192138-A
Country	US
Kind code	B2
Filing date	Feb 27, 2014
Priority date	Mar 6, 2013
Publication date	Jun 27, 2017
Grant date	Jun 27, 2017

Abstract

An optical fiber temperature distribution measurement device for measuring a temperature distribution along a longitudinal direction of an optical fiber is provided. The device includes: a light transmitter configured to input a train of code-modulated light pulses into the optical fiber; a light receiver configured to receive Raman back scattering lights generated by inputting the train of code-modulated light pulses into the optical fiber; a demodulator configured to perform a correlation processing between a measured signal output from the light receiver and a code string associated with a type of the code modulation performed by the light transmitter, and to demodulate the measured signal; a storage storing a correction data to be used to correct a distortion of the measured signal output from the light receiver when an impulsive pulsed light is output from the light transmitter; and a corrector configured to perform a correction to one of the measured signal output from the light receiver and a demodulated signal output from the demodulator, using the correction data stored in the storage.

First claim

What is claimed is:

1. An optical fiber temperature distribution measurement device for measuring a temperature distribution along a longitudinal direction of an optical fiber, the device comprising:
a light transmitter configured to input a train of code-modulated light pulses into the optical fiber;
a light receiver configured to receive Raman back scattering lights generated by inputting the train of code-modulated light pulses into the optical fiber;
a demodulator configured to perform a correlation processing between a measured signal output from the light receiver and a code string associated with a type of the code modulation performed by the light transmitter, and to demodulate the measured signal;
a storage storing a correction data to be used to correct a deviation of the measured signal output from the light receiver when an impulsive pulsed light is output from the light transmitter, the correction data being associated with temperatures;
a corrector configured to perform a correction to a demodulated signal output from the demodulator, using the correction data stored in the storage;
a temperature sensor configured to measure a temperature inside of the optical fiber temperature distribution measurement device and to input the temperature measured into the corrector; and
an operation unit configured to calculate a temperature distribution along a longitudinal direction of the optical fiber using a corrected signal corrected by the corrector,
wherein the corrector is configured to read out from the storage the correction data associated with the temperature measured by the temperature sensor and to perform the correction,
wherein the storage stores a first correction data to be used to correct a deviation of a measured signal associated with stokes light in the Raman back scattering lights and a second correction data to be used to correct a deviation of a measured signal associated with anti-stokes light in the Raman back scattering lights as the correction data, and
wherein the corrector is configured to correct a demodulated signal associated with the stokes light output from the demodulator using the first correction data, and to correct or a demodulated signal associated with the anti-stokes light output from the demodulator using the second correction data.

2. The optical fiber temperature distribution measurement device according to claim 1 , wherein the corrector is configured to interpolate the correction data associated with temperatures close to the temperature measured by the temperature sensor when the temperature measured by the temperature sensor does not correspond to any one of the temperatures, and to perform the correction using the interpolated data.

3. The optical fiber temperature distribution measurement device according to claim 1 , wherein the light receiver comprises a first light receiving circuit configured to receive stokes light included in the Raman back scattering lights and a second light receiving circuit configured to receive anti-stokes light included in the Raman back scattering lights.

4. The optical fiber temperature distribution measurement device according to claim 1 , wherein the corrector is configured to perform a convolution of the correction data and the demodulated signal and to correct the demodulated signal.

5. The optical fiber temperature distribution measurement device according to claim 1 , wherein the light transmitter comprises a code generator and a light source, and
wherein the code generator is configured to generate a driving signal and to input the driving signal into the light source, and the driving signal makes a train of light pulses output from the light source into a train of code-modulated light pulses.

6. The optical fiber temperature distribution measurement device according to claim 5 , further comprising an averaging circuit configured to operate by a timing signal from the code generator, to average data output from the demodulator, the data being generated every time each the train of light pulses output multiple times from the light source is input into the optical fiber, and to input the data averaged into the corrector.

7. The optical fiber temperature distribution measurement device according to claim 3 , wherein the operation unit is configured to calculate an intensity ratio of a data associated with the stokes light corrected by the corrector and received from the corrector and a data associated with the anti-stokes light corrected by the corrector and received from the corrector, and to calculate the temperature distribution along the longitudinal direction of the optical fiber using the intensity ratio.

8. A method of measuring an optical fiber temperature distribution, comprising:
a step of inputting a train of code-modulated light pulses into an optical fiber;
a step of receiving Raman back scattering lights generated by inputting the train of code-modulated light pulses into the optical fiber;
a step of performing a correlation processing between the measured signal received in the receiving step and a code string associated with a type of the code modulation and demodulating the measured signal;
a step of correcting a demodulated signal demodulated in the demodulating step, using a correction data to be used to correct a deviation of the measured signal, the correction data being associated with temperatures; and
a step of calculating a temperature distribution along a longitudinal direction of the optical fiber using a corrected signal corrected in the correcting step,
wherein the correcting step comprises a step of measuring a temperature inside of an optical fiber temperature distribution measurement device, and a step of correcting the demodulated signal using to the correction data associated with the temperature measured in the measuring step,
the correction data includes a first correction data to be used to correct a deviation of a measured signal associated with stokes light included in the Raman back scattering lights and a second correction data to be used to correct a deviation of a measured signal associated with anti-stokes light included in the Raman back scattering lights,
the receiving step receives stokes light and anti-stokes light in the Raman back scattering lights;
the demodulating step demodulates the stokes light and the anti-stokes light; and
the correcting step corrects a demodulated signal associated with the stokes light using the first correction data, and corrects a demodulated signal associated with the anti-stokes light using the second correction data.

9. The method of measuring an optical fiber temperature distribution according to claim 8 , wherein the correcting step interpolates the correction data associated with temperatures close to the temperature measured in the measuring step when the measured temperature does not correspond to any one of the temperatures, and corrects the demodulated signal using an interpolated data.

10. The method of measuring an optical fiber temperature distribution according to claim 8 , wherein the correcting step performs a convolution of the correction data and the demodulated signal to correct the demodulated signal.

11. The method of measuring an optical fiber temperature distribution according to claim 8 , wherein the inputting step comprises a step of inputting a driving signal into a light source, and a step of outputting a train of code-modulated light pulses associated with the driving signal from the light source.

12. The method of measuring an optical fiber temperature distribution according to claim 8 , further comprising, between the demodulating step and the correcting step, a step of aver

Assignees

• Yokogawa Electric Corp

Inventors

• Shida Hideo
• Oishi Kazushi

Classifications

• G01K2011/324

  Physics · mapped topic

• G01K11/32 Primary

  using changes in transmittance, scattering or luminescence in optical fibres · CPC title

• G01K11/324

  using Raman scattering · CPC title