Strain-Temperature Variation Dual Parameter Measurement Method Based on Chirped Grating

Abstract

The invention relates to a strain-temperature variable dual-parameter measurement method based on a chirped grating. The measurement method writes a convex chirped grating on an optical fiber. The chirp coefficient of the convex chirped grating is P. The length is L, the overall spectral width of the chirped grating is P×L, and the reflectivity of the L / 3~2L / 3 area in the middle of the chirped grating is higher than that of the two sides, forming a convex reflection spectrum, and m convex reflection spectra are arranged continuously to form Continuous spectrum sequence; then obtain the strain variable εz of the chirped grating, the temperature variable ΔT of the chirped grating and the position z′ of the point temperature change, the present invention utilizes the chirped optical fiber grating of convex shape for the first time when affected by the axial strain change and the sudden change of point temperature Spectral changes, while measuring the two parameters of point temperature change and axial strain, realized the millimeter-level distributed measurement of temperature and strain by the grating sensor in the true sense, greatly improving the measurement ability of high-order strain and the position of temperature change the accuracy.

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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