Novel Detection System for Micro-strain Signal Based on Demodulation Method of Tilted Fiber Bragg Grating Sensors

摘要

A research on distributed Fiber Bragg grating (FBG) demodulation system is based on tilted Fiber Bragg grating (TFBG). In order to separate temperature effect with fiber Bragg grating, we use two adjacent FBG (one used for sense, the another for reference ) which have the same central wavelength but different grating length, by parallel connection to make a sensing probe; Put the FBG keep close to equal thickness of rigidity cantilever beam of isosceles triangle, demodulate spectrum signal from sensing probe by using optical properties of main mode and side mode of TFBG and mechanical properties of cantilever. With the help of a computer to control cantilever beam's cyclic oscillating and collect transmission spectrum signals of TFBG at the same time, analytical processing data for real time display of await strain. Experimental results show that it is feasible to demodulate distributed optical Fiber Bragg grating by TFBG (resolution of micro-strain is 0.009~(με)), which solves the cross sensitivity of temperature and strain. The system is stably and reliable, low cost.