Weak grating array distributed vibration sensing system and method

A vibration sensing system and vibration sensing technology, applied in measuring devices, instruments, measuring ultrasonic/sonic/infrasonic waves, etc., can solve the problems of narrow frequency response bandwidth, affecting the signal-to-noise ratio of the system, and difficulty in low-frequency response, etc. The effect of improving stability, reducing noise floor, improving signal-to-noise ratio and frequency response range

Inactive Publication Date: 2020-05-15
WUHAN UNIV OF TECH
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Problems solved by technology

[0003] For the signal demodulation of the distributed weak grating vibration sensing demodulation system, the commonly used interferometers are Mach-Zehnder interferometer, Sagnac interferometer, and Michelson interferometer; the pulsed light is reflected back by the continuous weak grating, and finally reaches the interferometer Among them, interference occurs in the coupler after passing through two unequal length interference arms, so that the reflected light of adjacent weak gratings interferes; the interferometer with sensitive arms is easily disturbed by the external environment, such as the temperature of the chassis, the fan , external noise, vibration and other influences, resulting in a large noise floor for signal demodulation, thus affecting the signal-to-noise ratio of the system
In addition, most of the existing vibration sensing systems have a narrow frequency response bandwidth, and it is difficult to respond to low frequencies.

Method used

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  • Weak grating array distributed vibration sensing system and method
  • Weak grating array distributed vibration sensing system and method
  • Weak grating array distributed vibration sensing system and method

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Embodiment 1

[0034] The embodiment of the present invention provides a weak grating array distributed vibration sensing system, the schematic diagram of the structure, such as figure 1 shown, the system includes a narrow linewidth laser, an acousto-optic modulator, a circulator, a weak grating array, and a 3×3 coupler and photodetector;

[0035] The narrow linewidth laser is used to generate continuous light with a certain center wavelength and send it to the acousto-optic modulator; the acousto-optic modulator is used to modulate the continuous light into a corresponding double-pulse signal, and sending the double-pulse signal to a circulator; the circulator is configured to receive the double-pulse signal and transmit the double-pulse signal to a weak grating array, and the weak grating array reflects the double-pulse signal to the circulator; the circulator is also used to transmit the reflected double-pulse signal to the 3×3 coupler; the 3×3 coupler is used to cause the reflected doubl...

Embodiment 2

[0069] The present invention also provides a distributed vibration sensing method for a weak grating array, comprising the following steps:

[0070] The continuous light with a certain central wavelength is modulated into a corresponding double-pulse signal, and the double-pulse signal is transmitted to the weak grating array; the weak grating array reflects the double-pulse signal, so that the reflected double-pulse signal forms interference , generating an interference signal; acquiring the interference signal, and converting the interference signal into an electrical signal.

[0071] Preferably, the weak grating array distributed vibration sensing method further includes collecting and demodulating the electrical signal to form a demodulated signal; using an arctangent algorithm on the demodulated signal to obtain the difference between two adjacent gratings phase change between.

[0072] Preferably, the method for distributed vibration sensing of the weak grating array fu...

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Abstract

The invention discloses a weak grating array distributed vibration sensing system and a weak grating array distributed vibration sensing method, belongs to the technical field of fiber grating sensing, and solves the problems that demodulation by using a double-arm interferometer in the prior art is easily interfered by an external environment, the bottom noise is large, and the frequency responsebandwidth is relatively narrow. The weak grating array distributed vibration sensing system comprises: a narrow linewidth laser used for generating continuous light with a certain central wavelength;an acoustic optical modulator that is used for modulating the continuous light into a corresponding double-pulse signal; a circulator that is used for transmitting the double-pulse signal to the weakgrating array. The weak grating array reflects the double-pulse signal to a circulator; the circulator is also used for transmitting the reflected double-pulse signal to the 3 * 3 coupler; the 3 * 3coupler is used for enabling the reflected double-pulse signal to form interference and generating an interference signal; and the system also includes a photoelectric detector that is used for acquiring interference signals and converting the interference signals into electric signals. According to the invention, the system bottom noise is reduced, and the signal-to-noise ratio and the frequencyresponse range are improved.

Description

technical field [0001] The invention relates to the technical field of fiber grating sensing, in particular to a weak grating array distributed vibration sensing system and method. Background technique [0002] For the signal acquisition and demodulation end of the distributed weak grating vibration sensing demodulation system; according to the vibration sensing mechanism of the fiber grating, the vibration signal is essentially modulated into the interference signal, and the demodulation of the vibration signal is actually the phase Demodulation: At present, the commonly used phase demodulation methods in distributed sensing systems include quadrature (IQ) demodulation algorithm, phase carrier generation (PGC) detection method and 3×3 coupler demodulation algorithm; [0003] For the signal demodulation of the distributed weak grating vibration sensing demodulation system, the commonly used interferometers are Mach-Zehnder interferometer, Sagnac interferometer and Michelson ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G01H9/00
CPCG01H9/004
Inventor 唐健冠刘宇哲蒋言实邓艳芳甘维兵杨明红郭会勇
Owner WUHAN UNIV OF TECH
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