Measuring method for pulse pre-pump rayleigh BOTDA (Brilouin optical time domain analysis) temperature and strain

Abstract

Provided is a measuring method for pulse pre-pump rayleigh BOTDA (Brillouin optical time domain analysis) temperature and strain. Step pulsed light is injected into a sensing optical fiber, backward rayleigh scattering generated by a pre-pump pulsed light 1-order sideband serves as detection light to generate stimulated Brillouin scattering effect with sensing pulsed light in opposite-direction transmission, simultaneously sensing pulse and spontaneous Brillouin scattering signals generated by pre-pump pulsed light 0-order base band preexciting sound saves generate the stimulated Brillouin scattering effect, then the detection light returning to an incidence end and carrying stimulated Brillouin scattering information is utilized to obtain Brillouin frequency shift of each point of the optical fiber, and measurement of the temperature and the strain along the optical fiber is achieved according to the relations between the Brillouin frequency shift and the temperature / strain. According to the measuring method, the influence of non-local effect on system performance is greatly reduced, the conflict between the spatial resolution and measurement accuracy is effectively overcome, and the spatial resolution and the measurement accuracy are improved simultaneously.

Description

technical field [0001] The invention relates to a pulse pre-pump Rayleigh BOTDA temperature and strain measurement method based on time domain and spectrum domain shaping, and belongs to the field of measurement technology. Background technique [0002] Optical fiber distributed temperature / strain measurement technology based on the principle of Brillouin scattering has unique advantages such as high measurement accuracy, accurate positioning, and a distance of up to hundreds of kilometers. It has broad application prospects in the fields of health diagnosis, fault location and life assessment of steam pipelines, and geological disaster monitoring. [0003] At present, there are four mature technologies in the field of Brillouin scattering distributed optical fiber sensing at home and abroad: Brillouin Optical Time Domain Analysis (BOTDA), Brillouin Optical Time Domain Reflectometry (Brillouin Optical Time Domain Domain Reflectometry (BOTDR), Brillouin Optical Correlation D...

AI Technical Summary

Problems solved by technology

[0004] In the above-mentioned BOTDA sensing system with new mechanism and new method, on the one hand, due to the limitation of phonon lifetime, spatial resolution and measurement accuracy are mutually restricted and cannot be improved at the same time; on the other hand, due to the occurrence of continuous light and pulsed light SBS function, the measured signal at the detection end contains the state information of the optical fiber outside the sensing pulse interval, that is, there is the influence of non-local effect, which leads to the distortion of the Brillouin scattering spectrum and the fluctuation of the measured signal intensity, which in turn reduces the measurement accuracy. It is difficult to achieve long-distance, high spatial resolution and high-precision rapid measurement at the same time

Among them, the Rayleigh BOTDA system proposed by Q. Cui has the advantages of single light source, single-ended operation and non-destructive, but due to the use of Rayleigh scattering generated by the microwave-modulated continuous pulse base as the probe light, the non-local effect seriously affects the system performance. difficult to improve

Images