A single-ended vector botda dynamic strain measurement method and its measurement device

Abstract

The invention provides a single-ended vector BOTDA (Brillouin Optical Time Domain Analysis) dynamic strain measurement method, and a measurement apparatus thereof. The single-ended vector BOTDA dynamic strain measurement method comprises utilizing one composite optical signal to realize incidence from one end of a sensor fibre, wherein the back Rayleigh scattering light generated from the microwave modulation pulse substrate light in the sensor fibre is used as the probe light; the sensor pulse light generated from the microwave modulation pulse substrate light in the sensor fibre is used as the pump light; generation of the probe light and pump light are affected by the stimulated Brillouin scattering; the local oscillator light and the probe light carrying the stimulated Brillouin scattering information perform beat frequency in a photoelectric detector and extract the in-phase and quadrature components in an electric signal; the quotient of the in-phase and quadrature components and the phase shift of the stimulated Brillouin scattering has the relationship of arc tangent function so that a phase shift value is obtained; and finally according to the corresponding relationship curve stored in the computer between the phase shift and the dynamic strain, the corresponding dynamic strain value is obtained through modulation. As a nondestructive single-ended structure is introduced into a vector BOTDA, the single-ended vector BOTDA dynamic strain measurement apparatus is simple in structure and convenient for application, and is high in the response frequency band width and the measurement accuracy, and can improve the stability and reliability of a dynamic strain measurement system.

Description

technical field [0001] The invention relates to a method and device for realizing distributed measurement of dynamic strain by adopting a single-end vector BOTDA system, belonging to the field of measurement technology. Background technique [0002] Distributed sensing technology based on Brillouin Optical Time Domain Analysis (BOTDA) technology is widely used in power lines due to its unique advantages such as strong receiving signal, high measurement accuracy, accurate positioning and long sensing distance. Health diagnosis, fault monitoring and positioning of large-scale engineering structures in industries such as cables and equipment, oil and gas pipelines, construction, and water conservancy. [0003] The traditional BOTDA system needs to inject oppositely transmitted pump light and probe light at both ends of the fiber. When the frequency difference between the pump light and the probe light is the Brillouin frequency shift, stimulated Brillouin will occur in the sens...

AI Technical Summary

Problems solved by technology

However, in the Brillouin phase-shifted BOTDA system, the pump light and the probe light need to be respectively incident from both ends of the fiber, and the system structure is complex. When the fiber breaks, it will not be able to detect, and it is inconvenient and reliable to use in large-scale measurement occasions. Low, and SBS intensity is heavily affected by non-local effects

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