基于CORDIC算法的单频激光干涉信号处理系统半波长误差分析与消除

Analysis and Elimination of Half-wavelength Error in Homodyne Laser Interference Signal Processing System Based on CORDIC Algorithm

为了满足纳米级分辨率和高速处理,设计了基于CORDIC算法的激光干涉信号处理系统。研究发现信号处理系统存在半波长大小的粗大误差。对该半波长误差的特点与形成机理进行了研究,研究表明该半波长误差的根源为小数相位测量存在一定的误差区间,在干涉信号相位零点附近,该误差区间导致小数相位处于[2π^(-),0^(+)],具有不确定性;与整数相位结合时,可能产生半波长误差。在对半波长误差深入研究的基础上,给出修正表,提出了基于CORDIC算法相位补偿技术,以消除半波长粗大误差对激光干涉测量系统的影响。实验结果表明:在信号处理系统中,该相位补偿技术能够有效地消除半波长粗大误差,由CORDIC算法引入的总量化误差小于±0.05 nm。

In order to meet the nano-scale resolution and high-speed processing,a laser interference signal processing system based on CORDIC algorithm was designed. A gross error of half-wavelength in the signal processing system was founded during the research process. The characteristics and formation mechanism of the gross error were studied,and the research showed that the root cause of the half-wavelength error was the existence of a certain error interval in phase measurement,thus,near the zero-point of interferometric signal phase,the error interval caused the decimal phase to be in [2π^(-),0^(+)],which was uncertain. While the decimal phase combining with integer phase,the half-wavelength error might occur. On the basis of indepth research of the gross error,a CORDIC algorithm phase compensation technique based on the correction table was proposed to eliminate the influence of the half-wavelength error on the laser interferometry system. The experimental results showed that the phase compensation technique could effectively eliminate the half-wavelength gross error in the signal processing system,and the total quantization error introduced by the CORDIC algorithm was less than ± 0. 05 nm.