基于DSP的激光外差干涉信号处理方法  

Signal Processing Method of the Laser Heterodyne Interferometry Based on DSP

作　　者：赵思维[1] 严利平[1] 杨涛[1] 周砚江[1] 陈本永[1] 

机构地区：[1]浙江理工大学纳米测量技术实验室,杭州310018

出　　处：《浙江理工大学学报（自然科学版）》2011年第2期217-220,229,共5页Journal of Zhejiang Sci-Tech University(Natural Sciences)

基　　金：国家自然科学基金项目(90923026)

摘　　要：描述激光外差干涉测量的原理,设计基于DSP的激光外差干涉信号处理方法,用DSP的捕捉单元获取参考信号和测量信号的上升沿时间差,在捕捉单元中断中计算测量信号周期,由DSP将时间差转化为相位差并得出被测位移。采用信号发生器模拟两路输入信号,在0~360°范围内进行相位差测量实验,测量结果表明标准偏差为0.041°、线性拟合相关系数为0.999 89。以20 nm为步长在0~320 nm范围内进行位移测量实验,实验结果表明标准偏差为2.46 nm、线性拟合相关系数为0.999 71,验证了所设计的信号处理方法的可行性和实用性。The principle of laser heterodyne interferometry is introduced.The signal processing method of the heterodyne interferometer is designed based on digital signal processor（DSP）.Time difference between the rising edges of reference signal and measurement signal is obtained by the enhanced capture module（ECAP） of DSP.The period of measurement signal is calculated in the interrupt service routine of ECAP.Then the phase difference is calculated according to the time difference and period of measurement signal.Thus,the measured displacement can be obtained.The phase difference measuring experiment is carried out in the range of 0~360° by using a two channels function generator which outputs two square signals.The experimental result shows that standard deviation is 0.041° and the linearity coefficient is 0.99989.The displacement measurement experiment is carried out with step increment 20 nm in the range of 320 nm.The experimental result shows that the standard deviation is 2.46 nm and the linearity coefficient is 0.99971.These results show that the proposed signal processing method is reasonable and feasible.

关 键 词：纳米测量 激光外差干涉 信号处理 DSP 捕捉单元 

分 类 号：TH741[机械工程—光学工程]