The Demodulation Technique Of Fiber Optic Accelerometer Based On F-P Cavity

With the rapid development of modern science and technology,sensors are becoming more and more widely used in various fields,and the sensor has become the electronic organ of human information in the information society.Fiber optic acceleration sensor is an important branch of sensor,its high sensitivity,anti-electromagnetic interference,corrosion resistance,small size,light weight and a series of unique advantages,at the same time,its broad application prospects and unique advantages to its research has been high.In this paper,the optical fiber accelerometer based on F-P cavity and its demodulation system are studied.First of all,this paper introduces the research status and development trend of optical fiber sensor and micro accelerometer at home and abroad,and the theoretical basis of the fiber optic accelerometer is described,including the principle of mechanics and the working principle of F-P optical fiber sensor.And on this basis,using MATLAB software to simulate the working principle of F-P cavity,using ANSYS software to do finite element analysis of accelerometer,the correctness of the working principle of the fiber optic accelerometer is verified,which provides a solid theoretical basis for the follow-up work.Secondly,the circuit part of the accelerometer sensor system is designed,which is based on weak signal detection based on lock-in amplifier,the focus is on the phase-locked amplifier circuit.The circuit is divided into light source circuit and signal demodulation circuit,the light source circuit mainly includes modulation signal generation circuit,laser driver circuit,protection circuit,PID temperature regulation circuit;Signal demodulation circuit mainly includes photoelectric conversion circuit,preamplifier circuit,low-pass filter circuit,band-pass filter circuit,phase shift circuit,phase locked amplifier circuit,DC amplifier circuit and zero adjustment circuit.Last,a data acquisition system based on FPGA is designed,including AD,DA conversion module,UDP data transmission module,and host computer for data processing and storage.Completing the AD,DA conversion module and UDP data transfer module Verilog HDL programming to achieve a complete data acquisition system.The light source circuit,signal demodulation circuit and data acquisition system are debugged before the acceleration test,especially the laser drive and protection circuit and temperature control circuit,to ensure the safety of laser.Using the existing conditions of the laboratory,the acceleration detection system was built to test the performance of F-P optical fiber accelerometer,including the performance test of the laser,the accelerometer sensitivity experiment,the accelerometer resolution experiment,and the noise of the system is analyzed.The sensitivity and resolution of the accelerometer are good and meet the design requirements.