Optical time domain reflectometer simultaneously sensing temperature and stress

A technology of optical time domain reflectometer and sensing optical fiber, which is applied in the direction of transmitting sensing components, instruments, measuring devices, etc. by using optical devices, and can solve the separation and simultaneous detection of Rayleigh scattering signals and LPR temperature strain. Perception and other issues, to achieve the effect of small coherent Rayleigh noise

Inactive Publication Date: 2014-12-03
SHANGHAI INST OF OPTICS & FINE MECHANICS CHINESE ACAD OF SCI
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Problems solved by technology

This scheme improves the signal-to-noise ratio of the Brillouin scattering spectrum through the multiple superposition of the scattering spectrum, but does not involve the detection of t

Method used

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  • Optical time domain reflectometer simultaneously sensing temperature and stress
  • Optical time domain reflectometer simultaneously sensing temperature and stress
  • Optical time domain reflectometer simultaneously sensing temperature and stress

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Embodiment 1

[0037] Such as image 3 As shown, the electro-optic modulator is used for multi-wavelength modulation, the narrow linewidth laser (11) emits laser light near 1550nm, and the electro-optic modulator 13 modulated by the voltage-controlled oscillator 12 generates multi-wavelength lasers with flat amplitudes at intervals of 9-11 GHz , the multi-wavelength laser is divided into two beams by the first coupler 2, and one beam of light is modulated into a pulse by the acousto-optic modulator 32 controlled by the pulse signal generator 31, and the light pulse is injected into the circulator 4 after being amplified by the erbium-doped fiber amplifier 33 1 port, and then output from the 2 port of the circulator 4 to the sensing fiber 9, the backscattered light generated in the sensing fiber 9 is returned, and then output through the 3 port of the circulator 4. Another beam of multi-wavelength continuous laser is output after being scrambled by the polarizer 5, and enters the second coupl...

Embodiment 2

[0039] Such as Figure 4 As shown, the narrow-linewidth laser 11 emits laser light in the 1550nm band, and the phase modulator 13 modulated by the voltage-controlled oscillator 12 generates flat-amplitude multi-wavelength lasers with an interval of 9-12 GHz, and the multi-wavelength lasers pass through the first coupler 2 Divided into two beams of light: a beam of multi-wavelength continuous laser is modulated into pulses by the acousto-optic modulator 32 controlled by the pulse signal generator 31, and the optical pulse is amplified by the erbium-doped fiber amplifier 33 and then injected into port 1 of the circulator 4, from which the circulator Port 2 of 4 is injected into the sensing fiber 9 to generate backscattered light, and then output through port 3 of circulator 4. After another multi-wavelength continuous laser beam is scrambled by the scrambler 5, it enters the second coupler 6 at 50:50 together with the scattered light output from port 3 of the circulator 4 for co...

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Abstract

Disclosed is an optical time domain reflectometer simultaneously sensing temperature and stress. The system is based on parallel detection of Rayleigh and Brillouin scattered light and includes devices such as a multi-wavelength laser source, a light-pulse modulator, a balance detector, a microwave amplifier, a high-speed data acquisition card, a coupler and a circulator and the like. In the optical time domain reflectometer, the frequency interval of wavelengths of the multi-wavelength laser source is arranged to be in a range of 9-12 GHz, which is equivalent to a frequency shift quantity of Brillouin scattered light in a fiber. A heterodyne coherent detection method is used to carry out parallel detection on Rayleigh and Brillouin scattered spectra and temperature and stress information is demodulated through a Landau-Placzek ratio (LPR) and Brillouin frequency shift distribution; and at the same time, coherent Rayleigh noises are reduced and superposition of the scattered spectra improves the signal-to-noise ratio of the scattered light. The optical time domain reflectometer is capable of realizing simultaneous temperature and stress sensing of a distributed fiber sensing system, improving the signal-to-noise ratio of the scattered light and improving the sensing precision and distance.

Description

technical field [0001] The invention relates to an optical fiber Brillouin optical time domain reflectometer, in particular to an optical time domain reflectometer capable of simultaneously sensing temperature and strain. Background technique [0002] Brillouin optical time domain reflectometer is a new type of distributed optical fiber sensing technology based on Brillouin scattering, which can measure multiple physical parameters (such as temperature, strain, line loss, etc.), high spatial resolution, sensing With the advantages of long distance and high measurement accuracy, it can remotely monitor the temperature and strain changes along the optical fiber line. This kind of distributed optical fiber sensor has been widely concerned in many large structures, such as pipelines, offshore oil platforms, oil wells, dams, bridges, tunnels, cables, etc. The frequency shift and amplitude of Brillouin scattered light are linearly related to temperature and strain, but the amplit...

Claims

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Application Information

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IPC IPC(8): G01D5/353G01D21/02
Inventor 蔡海文曹玉龙叶青潘政清瞿荣辉
Owner SHANGHAI INST OF OPTICS & FINE MECHANICS CHINESE ACAD OF SCI
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