Brillouin optical time domain reflection measuring method based on quick fourier transform

Abstract

The invention interferes local reference light with Brillouin diffused light transferred back by a sensing optical fiber, a Brillouin diffused spectrum electrical signal generated completely passes through a broadband low pass wave filter, the sampling is performed by the high speed acquisition and the processing circuit, a quick speed Fourier transformation is performed, a Brillouin diffused spectrum is obtained; then a Lorentz fitting is performed, and a Brillouin frequency shift of each unit on the whole optical fiber is obtained finally; the relation of the Brillouin diffused spectrum, and the strain or the temperature is utilized to realize a full-distribution type measurement of the strain or the temperature. The whole Brillouin diffused spectrum on the whole sensing optical fiber can be obtained in an impulse detecting circle by a processing method of the high speed acquisition, and the processing circuit and the quick speed Fourier transformation adopted by the invention, the measuring speed is improved to an order of magnitude compared with the prior technology on the premise of not decreasing the resolution of a measuring space and the measuring accuracy, thereby improving a speech to noise ratio to more than a plurality of times, the measuring accuracy is improved to a great extent, and the structure of the invention device is simple.

Description

technical field [0001] The invention relates to a distributed optical fiber sensing system for fully distributed measurement of strain and temperature, specifically a fast Fourier transform-based Brillouin sensing system that uses Brillouin scattering in optical fibers to realize fully distributed measurement of strain and temperature Optical Time Domain Reflectometry Method. Background technique [0002] The fully distributed optical fiber sensing technology uses the entire optical fiber as the sensing element, and utilizes the scattering phenomenon in the optical fiber to realize the continuous distribution measurement of the physical quantity to be measured (strain, temperature, etc.) on the sensing optical fiber as a function of time and space. Compared with the quasi-distributed optical fiber sensing technology based on the point sensor array, the fully distributed optical fiber sensing technology has a broader application prospect. Brillouin optical fiber time domain ...

AI Technical Summary

Problems solved by technology

[0007] The problem to be solved by the present invention is: the existing Brillouin optical time domain reflectance measurement method needs multiple measurements to obtain the required Brillouin scattering spectrum data, and the measurement time is relatively long. Although the bandwidth of each measurement can be increased to Reduces measurement time, but results in reduced measurement accuracy

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