基于等效时钟法的干涉仪速度信息获取研究

Study on velocity information acquisition of the interferometer based on equivalent clock method

为了提升傅里叶变换光谱仪(Fourier transform infrared spectroscopy,FT-IR)的性能,设计了一种基于等效时钟法的高精度速度信息获取系统。激光信号经过干涉仪形成干涉信号,通过放大、滤波、整形,成为数字电路识别的脉冲信号。基于速度信息获取的数学原理,对基于T法测量获取速度信息的方法进行了误差分析,并提出基于等效时钟法的速度信息获取方法。现场可编程门阵列(field programmable gate array,FPGA)读取脉冲信号后,根据等效时钟法计算光程差速度值。仿真分析与实验结果表明,当He-Ne激光干涉信号频率为9kHz时,基于等效时钟法的速度信息获取误差仅为0.01%,实现了高精度的光程差速度信息获取。对提高干涉仪系统的控制精度和光谱仪的信噪比具有重要意义。

To improve the performance of Fourier transform spectrometer,a high-precision velocity information acquisition scheme based on equivalent clock method is designed.The laser signal forms an interference signal through the interferometer,which is amplified,filtered and shaped into a pulse signal recognized by the digital circuit.Based on the mathematical principle of velocity information acquisition,the error of obtaining velocity information based on T method is analyzed,and the velocity information acquisition method based on equivalent clock method is proposed.After reading the pulse signal,field programmable gate array(FPGA)calculates the optical path difference velocity value according to the equivalent clock method.Simulation analysis and experimental results show that when the frequency of He-Ne laser interference signal is 9 kHz,the measurement error of velocity feedback based on equivalent clock method is only 0.01%,and high precision optical path difference velocity information acquisition is realized.This is of great significance to improve the control accuracy of the interferometer system and the signal-to-noise ratio of the spectrum.