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Differential pair grating demodulating technology for fiber grating sensor stress measurement

A fiber grating and stress measurement technology, applied in the field of optical sensors, can solve the problems of low stress demodulation sensitivity, high price, low stress resolution, etc., achieve wide application value and eliminate measurement errors

Inactive Publication Date: 2012-11-07
SOUTHWEST JIAOTONG UNIV
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Problems solved by technology

[0004] Among the above methods, method 1) is only suitable for laboratory use; methods 2) and 3) are suitable for applications with higher demodulation accuracy, but the price is higher; method 4) has a simple structure, but the sensitivity of stress demodulation is not high, and is suitable for Applications requiring low stress resolution, such as train axle counting systems

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  • Differential pair grating demodulating technology for fiber grating sensor stress measurement
  • Differential pair grating demodulating technology for fiber grating sensor stress measurement
  • Differential pair grating demodulating technology for fiber grating sensor stress measurement

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Embodiment Construction

[0017] Such as figure 1 As shown, the ASE light source (100) sends the broadband optical signal into the circulator (101), the laser signal is reflected by the FBG3 (200) to the circulator (101), and then divided into two beams with the same intensity by the coupler (102) Light. The Bragg wavelength (central wavelength) of FGB1 (201) is the same as the sensing grating FBG3 (200), while the Bragg wavelength of FBG2 (202) has a positive offset (or negative offset) relative to the central wavelength of FBG3 (200) ), the offset is equal to the 3dB bandwidth of the sensing grating FBG3.

[0018] The fiber grating reflection spectrum can be approximated by a Gaussian function (such as figure 2 shown), then the distribution of the light signal reflected by FBG3(200) can be expressed as:

[0019] I s (λ)=S(λ B )G(λ) (1)

[0020] Among them, S(λ B ) represents the characteristic spectrum of the ASE light source (100), which is a wavelength-independent quantity as mentioned abov...

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Abstract

The invention discloses a differential pair grating demodulating technology for fiber grating sensor stress measurement, wherein one sensing grating and at least two reference gratings are adopted, spectrum parameters of one of the reference gratings are the same as that of the sensing grating, and the Bragg wavelength of the other reference gratings is subjected to micro shift relative to the sensing grating. Optical power signals which pass through the reference gratings by means of transmission are respectively acquired, and measurement data at corresponding time points are subtracted to obtain a stress demodulating curve. Compared with the common single-channel matching grating demodulating manner, the differential pair grating demodulating technology for the fiber grating sensor stress measurement is increased by about twice in the aspect of sensitivity for stress measurement, and the measurement error caused by fluctuation of output light power of a light source can be eliminated. The invention can be applied to a fiber grating stress sensing system so as to realize high-sensitivity stress monitoring of traffic safety monitoring systems for high-speed railways, urban rail trains, bridge and tunnel structures and the like, and has a wide application value in fields, such as intelligent buildings, geological and geotechnical engineering and the like.

Description

technical field [0001] The invention relates to an optical sensor, in particular to a sensing method for improving detection performance by utilizing differential pair grating demodulation technology in the field of optical fiber grating sensing. Background technique [0002] Compared with the commonly used electrical sensing technology, fiber optic sensors have excellent performances such as anti-electromagnetic interference, light weight, small size, good insulation performance, high temperature resistance, and corrosion resistance. Has been more and more applications. Compared with the distributed optical fiber sensing technology, the fiber grating sensor has higher precision and better real-time performance. [0003] Currently, the commonly used fiber grating demodulation techniques are as follows: 1) spectrometer detection method. A spectrometer is used to detect the wavelength change of the output optical signal. 2) Tunable light source method. The method adopts a ...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): G01L1/24
Inventor 张志勇闫连山潘炜罗斌张兆亭温坤华
Owner SOUTHWEST JIAOTONG UNIV
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