High-spatial resolution long-distance distributed optical fiber temperature strain sensing system

Abstract

The present invention relates to a high-spatial resolution long-distance distributed optical fiber temperature strain sensing system. The system injects an optical pulse pair of which the pulse widths have a slight difference in a sensing optical fiber based on a pulse pair secondary frequency spectrum differential technology, detects and acquires a time domain brillouin scattering signal generated by each pulse, and adopts two sets of different time window widths to extract the data separately for the spectral analysis, and carries out the secondary frequency spectrum differential operation based on the obtained four sets of brillouin frequency spectrum data, thereby obtaining the space position sensing information covered by the pulse width difference of the optical pulse pair corresponding to the secondary differential brillouin spectrums, and improving the spatial resolution. By designing the pulse widths and the pulse width difference of the optical pulse pair in the system reasonably, the action of a brillouin nonlinear effect is full, and the information within a sensing range of dozens of kilometers is acquired on the condition of keeping a higher signal-to-noise ratio of the system, so that the distributed optical fiber temperature strain sensing system of high spatial resolution (cm magnitude), long distance (greater than 50 kilometers) and high measurement precision (plus or minus 1 DEG C, plus or minus 20 Mu Epsilon) can be realized.

Description

technical field [0001] The invention relates to the technical field of distributed optical fiber temperature and strain measurement, in particular to the second Brillouin spectrum difference based on pulse pair while maintaining the performance parameters of long distance (>50 kilometers) and high measurement accuracy (±1°C, ±20με). The technology realizes a distributed optical fiber temperature and strain sensing system with a spatial resolution of centimeter level. Background technique [0002] In the Brillouin scattering-based distributed optical fiber sensing (BOTDR) system, the incident pulse light interacts with the acoustic phonons in the fiber to produce back Brillouin scattered light, which is relative to the incident light The frequency shift is affected by temperature and strain. For single-mode optical fibers in the communication band, the frequency shift of Brillouin spontaneously scattered light relative to the incident light is about 11GHz, and the linear c...

AI Technical Summary

Problems solved by technology

These technologies adopt different technical solutions to achieve high spatial resolution sensing, but they all introduce some new problems, such as shortened sensing distance, presence of sensing loops, etc., and are not suitable for actual large-scale projects. health monitoring occasions

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