Strain-temperature change two-parameter measuring method based on chirped grating

Abstract

The invention relates to a strain-temperature change two-parameter measuring method based on chirped grating. The measuring method comprises the steps of: inscribing an inverted T-shaped chirped grating on an optical fiber, wherein the chirp coefficient of the inverted T-shaped chirped grating is P, the length of the chirped grating along the axial direction of the optical fiber is L, the width of the whole spectrum of the chirped grating is P*L, and the reflection rate of L/3-2L/3 region in the middle of the chirped grating is higher than that of two sides; forming an inverted T-shaped reflection spectrum; continuously arranging m inverted T-shaped reflection spectrums to form a continuous spectrum column; and obtaining the strain capacity epsilon z, temperature change quantity delta T of the chirped grating and point temperature change position z'. According to the strain-temperature change two-parameter measuring method based on chirped grating provided by the invention, the spectrum change situation in the influence of axial strain change and point temperature sudden change on the inverted T-shaped chirped fiber grating is utilized for the first time, and two parameters of the point temperature change and the axial strain are measured at the same time, so that the millimeter distribution measurement of a grating sensor on the temperature and the strain is realized in true sense, and the measurement capability of high-order strain and the accuracy of temperature change position are greatly improved.

Description

technical field [0001] The invention relates to a strain-temperature variable dual-parameter measurement method based on a chirped grating, and belongs to the technical field of sensors. Background technique [0002] Fiber Bragg grating sensors are widely welcomed for their advantages of small size, light weight, strong reusability, and high sensitivity. However, the traditional fiber grating is limited by its own length and other conditions, and it cannot detect the strain and temperature changes at precise positions. It can only achieve quasi-distributed detection, but cannot achieve distributed measurement in the true sense. As an important fiber optic device, chirped fiber gratings have been widely used in the fields of filtering, dispersion compensation, pulse shaping and fiber optic sensing technology. People have proposed a variety of methods to realize chirped fiber gratings, mainly including direct preparation methods and indirect realization methods based on perio...

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Problems solved by technology

[0003] The University of Southampton, UK, and the Jian Shuisheng research group of Beijing Institute of Technology have reported the successful writing of ultra-long gratings, which shows the maturity and progress of the grating manufacturing process, but has not yet used a long chirped grating to measure temperature-strain simultaneously Reporting of two parameters

[0004] In addition, in the actual measurement environment, the fiber grating often needs to be embedded in the composite material for actual measurement, and the external field it receives is often a non-uniform external field, which will cause the external force chirp of the fiber grating

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