Research On Optimization And Application Of MEMS Spectrometer Data Acquisition System Based On FPGA

Traditional Fourier transform near infrared spectrometer(FT-NIR)is a desktop-level equipment with large volume and high cost.And the micro spectrometer based on MEMS technology not only has the advantages of small volume,low cost and low power consumption,but also is beneficial to on-site on-line detection.It can be widely used in medical,food and pharmaceutical analysis fields,and is a hotspot of current research.This paper designs a small,compact and low-cost FT-NIR using FPGA as the control processor of the data acquisition system,and using MEMS electrothermal micro-mirror in optical structure,and optimizes its data acquisition system.At the same time,the near infrared absorption spectra of common drugs were measured by this spectrometer,its main content is as follows:(1)The noise generated by the quantization error of analog-digital converter is simulated and analyzed,the spectrum of analog-digital converter with different resolution is established,and the influence of quantization error on the spectrum is analyzed.The simulation results show that the higher the resolution of analog-digital converter,the more accurate the spectrum is,conversely the higher the spectral distortion is.(2)The main components of the spectrometer are selected,including the photoelectric sensor,MEMS micromirror and control processor.In order to meet the requirement of digital resampling of the sample optical interference signal,a dual Michelson interferometer is designed to realize the interference of sample light and reference light.(3)A synchronous acquisition circuit and a MEMS drive circuit of low noise interference signals are designed.Interferometric signal synchronous acquisition circuit includes I/V conversion circuit,voltage amplifier circuit,bandpass filter circuit,differential amplifier circuit and analog-to-digital conversion circuit.MEMS drive circuit includes digital-analog conversion circuit and voltage amplifier circuit.(4)The FPGA logic is designed using Verilog language in Quartus software,including MEMS driver,data acquisition,FFT,UART and RAM.And the timing simulation and function verification are carried out for the MEMS driver module and the data acquisition module.By using the near infrared light of 1310 nm,the function of the whole system is verified and the spectrum is obtained successfully.The MEMS near infrared spectrometer designed in this paper can be used in biomedical detection,clinical detection and drug detection.For example,blood glucose and blood oxygen of blood can be measured in clinical examination,and the early diagnosis and efficacy observation of benign and malignant tumors can be carried out.