Distributed optical fiber sensing system based on Rayleigh and Brillouin scattering fusion

A Brillouin scattering and distributed optical fiber technology, which is applied in the direction of using optical devices to transmit sensing components, convert sensor outputs, instruments, etc., can solve the problems of difficult multi-parameter fusion sensing, low output power density of light sources, etc. Efficiency coupling, the effect of improving output power density

Pending Publication Date: 2021-06-22
CHINA COAL TECH & ENG GRP CHONGQING RES INST CO LTD +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0005] The invention provides a distributed optical fiber sensing system based on the fusion of Rayleigh and Brillouin scattering, which solves the technical problem that the existing optical fiber sensing system is difficult to simultaneously realize multi-parameter fusion sensing due to the low output power density of the light source

Method used

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  • Distributed optical fiber sensing system based on Rayleigh and Brillouin scattering fusion
  • Distributed optical fiber sensing system based on Rayleigh and Brillouin scattering fusion

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Embodiment 1

[0029] The embodiment is basically as attached figure 1 shown, including:

[0030] The light source is used to generate and output the detection optical signal and the local oscillator optical signal; the light source includes a fiber optic cone, which is formed by melting and drawing a number of optical fibers; the fiber optic cone includes a large end and a small end, and the large end has a There are loose pigtails, and each fiber of the loose pigtails is connected to a laser with a collimator lens combination through a connector;

[0031] a modulation unit, configured to receive the detection light signal and modulate to generate pulsed light, and output the pulsed light to the optical fiber to be tested;

[0032] The coherent detection unit is used to receive the local oscillator optical signal and the back reflection signal generated by the optical fiber to be tested according to the Rayleigh scattering and Brillouin scattering effects, and mix the local oscillator opti...

Embodiment 2

[0042] The only difference from Embodiment 1 is that it also includes an optical circulator, the first end of the optical circulator is connected to the modulation unit, the second end of the optical circulator is connected to the optical fiber to be tested, and the third end of the optical circulator is connected to the coherent detection unit. The laser light emitted by the laser is divided into 80% of the probe light and 20% of the local oscillator light through the optical coupler. The probe light is modulated by the acousto-optic modulator to obtain pulsed light. output to the fiber under test. Considering the Rayleigh scattering and Brillouin scattering effects in the optical fiber to be tested, the back reflection signal generated by the optical fiber to be tested is input from the second end and then output from the third end.

Embodiment 3

[0044] The only difference from Embodiment 2 is that in this embodiment, the optical fiber 5 is used in winter in Northeast China, the daily temperature difference between day and night can be above 20-30°C, and the temperature change rate can reach 4-6°C / h; a part of the optical fiber 5 One is buried in the soil and the other is exposed to the air. Soil temperature will show seasonal fluctuations and diurnal changes with the change of air temperature near the surface; at the same time, due to the influence of periodic diurnal and annual changes in solar radiation, soil temperature will also change accordingly, making the annual change of soil temperature show It is a sinusoidal function, and the variation range of temperature decreases with the increase of soil depth. At a certain depth, the amplitude can be considered to be approximately zero. In addition, due to the different heat transfer coefficients of soil and air, the temperature of the soil is usually higher than that...

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Abstract

The invention relates to the technical field of distributed optical fiber sensing, in particular to a distributed optical fiber sensing system based on Rayleigh and Brillouin scattering fusion. The system comprises a light source, a modulation unit, an coherent detection unit, a Rayleigh demodulation unit and a Brillouin demodulation unit, wherein the light source is used for generating and outputting a detection light signal and a local oscillation light signal; the light source comprises an optical fiber light cone, and the optical fiber light cone is formed by melting and drawing a plurality of optical fibers; the modulation unit is used for receiving the detection light signal and modulating to generate pulsed light; the coherent detection unit is used for mixing the local oscillation optical signal and the back reflection signal to obtain an optical heterodyne electric signal; the Rayleigh demodulation unit is used for demodulating according to the Rayleigh scattering signal to obtain reflection, attenuation and vibration information along the optical fiber; and the Brillouin demodulation unit is used for demodulating according to the Brillouin scattering signal to obtain stress and temperature information of the optical fiber to be measured. The optical fiber light cone is designed in the light source, and the output power density of the light source can be effectively improved.

Description

technical field [0001] The invention relates to the technical field of distributed optical fiber sensing, in particular to a distributed optical fiber sensing system based on the fusion of Rayleigh and Brillouin scattering. Background technique [0002] As far as the current optical fiber sensing technology is concerned, it is mainly divided into point sensing and distributed sensing. The former is only suitable for monitoring a limited number of key positions. When the number of positions to be monitored increases, the number of sensing units required , cost and technical difficulty will increase significantly; the latter regards every point along the optical fiber as a sensing unit, and the size of each point (that is, the spatial resolution) is determined by the input detection light signal, which can be compared relatively quickly Under the condition of low cost, the number of sensing units along the optical fiber is greatly increased. At present, in the field of distri...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G01D5/353
CPCG01D5/35364G01D5/35361
Inventor 孙维张建鑫孙中光王璇戴书球钟宇李勇张宇梁帅谭一川罗剑
Owner CHINA COAL TECH & ENG GRP CHONGQING RES INST CO LTD
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