Design Of Microstrain Sensing System Based On Fiber Grating

The paper makes use of F-P interferometer as sensing head to design and study experimentally microstrain measurement system. Based on profound analysis on present studies home and abroad, the paper summarizes development trend of fiber grating sensor. According to practical need of fiber grating microstrain sensing, the paper presents sensing system in three aspects: design of sensing head and reusable strain sensing tuning structure, digital signal processing session.Starting from coupling mode model, the paper analyzes sensing mechanism and establishes sensing models of fiber grating. After comparing several multiplexing techniques, the paper adopts spectrometer to modulate signals, equal-thickness triangle cantilever magnetically controlled to provide force on order to generate strain. The paper confirms theoretically and experimentally feasibility of the designed sensing system.Thereafter, the paper deduces theoretical sensing models of fiber grating F-P interferometer, and confirms unique advantages in microstrain measurement field. Especially, several performances index of FBG sensing head are deduced. With respect to force generation, the paper analyzes a few methods commonly used and determines to design a sensing structure magnetically controlled. At the same time, mathematical models on the tunable structure are given. Simulated experiments verify that designed structure is able to provide force fiber grating needs produciblly.Experiments on microstrain measurement characterizations of fiber grating are carried out, and wavelet filtering method is adopted to denoise gathered sensing signals, which gives perfect experimental results.