外差干涉非线性误差修正方法研究

基于对外差干涉测量信号和参考信号进行光滑滤波处理的方法，提出了一种外差式激光干涉仪非线性误差修正方法。在实验系统中，采用混频技术将两路光频信号降低到通用数据采集系统频率范围内进行同步双通道实时采集；采用改变光传输介质折射率的方法模拟产生纳米数量级微位移。实验结果表明，所提出的修正方法使实验用外差干涉仪测量不确定度由20nm降低到10nm。

A Novel Method for Reducing Greatly the Nonlinear Errors in Heterodyne Laser Interferometry

As our analysis shows that the existing approach for reducing nonlinear errors in heterodyne laser interferometry is not quite satisfactory, we propose a novel and better method to do this job. In this novel method, the measurement signals and reference signals are smoothed to filter out the higher-order nonlinear errors. The key to this novel method was found after much discussion with Professor Guo Yanzhen(Y.Z. Guo) of Xi'an University of Science and Technology. This key is described as follows: mixing frequency technology was introduced to transform the megahertz light signals into kilohertz electric signals that can be handled by data acquiring systems; the mixed-frequency signals are acquired synchronously through double data acquiring channels and the phase difference between the reference and measuring light beams is evaluated. The experimental results indicate preliminarily that the proposed method can reduce the uncertainty of the heterodyne interferometer from 20 nm to 10 nm. This novel method is generally applicable to the nonlinearity compensation of heterodyne interferometers.