Research On Fiber Bragg Grating Signal Processing System Based On Dual-Wavelength Differential Detection

Recently,fiber Bragg gratings(FBGs)have been widely used in the field of fiber optic sensing due to their advantages such as immunity to electromagnetic interference,small size,corrosion resistance,and low transmission loss.This places higher demands on demodulation accuracy,processing speed and cost of FBGs signal processing system.To solve the problem of low accuracy,slow speed,high cost,and large size in existing FBG signal processing systems,this thesis researched the FBG signal processing system based on dual-wavelength differential demodulation,and designed the signal processing system using microcontroller and field programmable gate array devices to achieve high precision,integration,miniaturization,and low cost.The main research contents are as follows:1.Analyzing in detail the performance of the FBG signal processing system based on dual-wavelength differential demodulation.By theoretical simulation analysis,sensitivity,linear range,spatial resolution,and temperature resolution of the dualwavelength differential demodulation method were analyzed and simulated.The simulation results show that the measurement range decreases with the increase of temperature resolution.2.Designing the hardware part of the FBG signal processing system.The laser,detector,ADC,microcontroller,and field programmable gate array devices were integratedly designed to achieve miniaturization,low cost,and high precision.The hardware design includes power supply design,laser driver design,detection system design,digital system design,and PCB design of the FBG signal processing system.In the detection system design,the output signal was designed to meet the experimental requirements by designing cross-resistance amplification circuits,inverting amplification circuits,and single-ended to differential conversion circuits.Hardware design is the basis and focus of the entire system and also a prerequisite for the implementation of various functions.3.Realizing digital logic design,software writing,and system debugging of the FBG signal processing system.This system can achieve human-computer interaction,algorithm processing,data transmission,and storage functions.The high-precision realtime sensing and measurement were achieved by this system with low cost.4.Testing the temperature resolution and spatial resolution of the designed FBG signal processing system.In the temperature resolution test,when the wavelength difference of the incident laser was 0.50 nm,the system achieved a temperature resolution of 0.09 ℃.In the spatial resolution test,the system achieved a spatial resolution.