Double-pulse phase sensitive OTDR (optical time-domain reflectometer) integrated with weak reflection grating, and method for double-pulse phase sensitive OTDR

A weak reflection grating, time domain reflectometer technology, applied in the use of wave/particle radiation, measuring devices, instruments, etc., can solve the problems of small scattered light power, narrowing the sensing range of the sensing system in space, etc. The effect of the signal-to-noise ratio

Active Publication Date: 2016-05-04
NANJING UNIV
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Problems solved by technology

Although the use of weak reflection grating arrays can solve the problem of small back Rayleigh scattered optical power to a certain extent, most of the current sensing methods using weak reflec

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  • Double-pulse phase sensitive OTDR (optical time-domain reflectometer) integrated with weak reflection grating, and method for double-pulse phase sensitive OTDR
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  • Double-pulse phase sensitive OTDR (optical time-domain reflectometer) integrated with weak reflection grating, and method for double-pulse phase sensitive OTDR

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[0031] Below in conjunction with accompanying drawing, technical scheme of the present invention is described in further detail:

[0032] refer to figure 1 , the high signal-to-noise ratio dual-pulse phase optical time-domain reflectometer fused with a weak reflection grating of the present invention includes a narrow linewidth laser 1, an optical modulator 2, a circulator 3, a data acquisition device 4, an avalanche detector 5, and a weak reflection Grating array, sensing fiber 7, pulse signal generator 8. The continuous light emitted by the narrow linewidth laser 1 is modulated into a detection light pulse by the light modulator 2, and the detection light pulse includes two light pulses before and after, such as image 3 As shown, it is called detecting double pulse, and the detecting double pulse enters the sensing fiber 7 from the A port of the circulator 3, and the sensing fiber is covered with a weak reflection grating array along the line, and the weak reflection grati...

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Abstract

The invention discloses a double-pulse phase sensitive OTDR (optical time-domain reflectometer) integrated with a weak reflection grating, and the OTDR comprises a narrow-pulse laser, a light modulator, a circulator, a data collection device, an avalanche detector, a weak reflection grating array, a sensing optical fiber, and a pulse signal generator. The invention also discloses a vibration measurement method for the OTDR. The OTDR employs a mode of integrating with the weak reflection grating, and improves the signal to noise ratio of a system. Through employing a double-pulse detection method, the OTDR solves a problem that most of grating sensing is just sensitive to the position event of a grating, and is enabled to be sensitive to all events of the sensing fiber along a line. Because the signal to noise ratio of the system is very high, the OTDR can measure the high-frequency vibration of limit frequency under the limiting of the length of the sensing fiber, and also can measure the low-frequency vibration (less than 10 hertz).

Description

technical field [0001] The invention relates to the field of optical fiber sensing, in particular to a double-pulse phase-sensitive optical time-domain reflectometer combined with a weak reflection grating and a method thereof. Background technique [0002] Phase-sensitive optical time-domain reflectometry (Φ-OTDR) realizes the detection of external disturbances by detecting the change of the interference signal of back Rayleigh scattered light in the sensing fiber. It has high sensitivity, distributed measurement, and long sensing distance. The advantages. Φ-OTDR was first proposed by H.F.Taylor (TaylorHF, LeeCE.Apparatus and method for fiberoptic intrusionsensing[P].1993-.http: / / www.google.co.uk / patents / US5194847) in 1993, and its basic structure is similar to OTDR , the only difference is that a narrow linewidth laser is used as the light source, so that the scattered light of the superimposed scattering centers interferes with each other, forming a jittering backscatter...

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Application Information

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IPC IPC(8): G01H9/00
CPCG01H9/004
Inventor 王峰周玲张旭苹刘涛
Owner NANJING UNIV
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