Fiber Bragg Grating Temperature/Strain Demodulator Design

With the rapid development of fiber-optic communication and fiber-optic sensing,Fiber Bragg Grating sensors have become the fastest growing and most widely used fiber-optic sensors.FBG sensors are widely used in aerospace,bridge tunnels,precision instruments,wearable devices and other sensing fields due to their small size,light weight,corrosion resistance,electromagnetic interference resistance and easy networking.At present,various fiber Bragg grating demodulators based on different demodulation schemes have appeared at home and abroad,but most of these demodulators are expensive and limit their application in practical engineering.Therefore,it is very important to design a fiber Bragg grating demodulator that is suitable for industrial applications and cost-effective.In this paper,the fiber Bragg grating demodulation system is deeply researched.Based on the demodulation products at home and abroad,a fiber Bragg grating demodulator for engineering applications is designed and developed.The demodulator is based on a tunable F-P filter for sensor demodulation,and has the advantages of wide measurement range,fast dynamic response,easy to use networking and is suitable for engineering applications.This paper mainly studies from the following aspects:(1)Based on the optical fiber sensing technology,theoretical analysis and research on the fiber grating sensing characteristics and demodulation principle are carried out.Several fiber Bragg grating demodulation schemes and FBG sensors commonly used in the industrial field are analyzed and illustrated.(2)Design the experimental scheme of the fiber Bragg grating demodulation system,select the key components,and build the demodulation system.The tunable F-P filter is calibrated and calibrated by using the F-P etalon and the reference grating to form a reference wavelength to improve the demodulation accuracy of the system.(3)Combine LabVIEW and MATLAB to compile the PC software,and design a software program that conforms to industrial applications.Aiming at the algorithm optimization problem in the process of peak finding,the effects of filtering algorithm and curve fitting algorithm on peak accuracy are studied and verified by experiments.(4)Analyze the performance of the fiber Bragg grating demodulator through experimental tests,and test the stability,repeatability,temperature and strain of the demodulator.The experimental results show that the designed fiber Bragg grating demodulator has a repeatability of ±2 pm and a resolution of 1 pm;the demodulator has a temperature detection accuracy of ±0.2 °C,the corresponding variable detection accuracy is 10 με,and the strain detection range is 0 to 6000με.