Spectrum Acquisition And Processing System Of Fourier Transform Spectrometer Based On FPGA

Fourier Transform Spectrometer mainly works in the infrared or near-infrared band.It can be used for the composition analysis of a variety of chemical substances and biological materials.It has high sensitivity and accuracy and is widely used in food safety,environmental monitoring,industrial and agricultural production and many other areas.Traditional Fourier transform spectrometer is used in laboratory or analysis center for its large volume and high cost.But the micro Fourier transform spectrometer based on Micro-electro-mechanical Systems(MEMS)has compact structure and small volume,which can realize on-site detection.In order to obtain real-time spectral information,a high-speed interferogram acquisition and processing system is required.Based on the micro Fourier transform spectrometer using MEMS micro mirror instead of moving mirror structure,this paper designs a spectrum acquisition and processing system.The system uses FPGA(Field Programmable Gate Array)as the core processor with the advantages of small volume,high integration,fast processing speed.The main contents of this article are as follows:(1)The Michelson interference structure is designed to realize the interference between the reference laser and the sample light based on the resonant MEMS micromirror.And the corresponding spectrum acquisition and processing system is designed based on FPGA.The phase error of the sinusoidal variation introduced by the sampling delay is simulated and analyzed.The simulation results show that the greater the amplitude of the phase error,the higher the spectral distortion.And a sampling delay measurement and correction method is designed.(2)The FPGA logic is designed using Verilog language in Vivado software,including clock and reset module,mirror control and data acquisition module,ADC control module,gain control module,FFT module,Ethernet communication module.And the function simulation of the module was carried out.(3)An experimental platform is built to verify the function of the spectrum acquisition and processing system.The FPGA and MATLAB processing results are consistent,indicating that the design and function of the spectrum acquisition and processing system are correct.The whole system of Fourier transform spectrometer was built.By using 1550 nm laser and broadband light source,the function of the whole system is verified and the corresponding spectrums are successfully measured.This Fourier transform spectrometer can complete 2500 spectrum measurements per second.