无非线性误差多自由度外差干涉测量系统研究

High precision measurement of multi-degree-of-freedom is always a research focus in the fields of metrology and precision engineering, and remains a measurement problem to be well solved. Heterodyne laser interferometry is a widely applied method for precision measurement for its high resolution, minimum dead path and immunity to the environmental disturbance. However, due to the frequency mixing caused by inevitable imperfectness in optical system, a nonlinear relationship exists between the measured phase and the respective displacement, which limits the accuracy of the heterodyne interferometer at the nanometer level. This research focuses on this problem and will achieve a multi-degree-of-freedom precision measurement method for high precision displacement platform. Based on the research and theoretical analysis of measuring principles of plane mirror interferometer, mathematical models for multi-degree-of-freedom measuring are established. According to the nonlinearity theory, a general laser source and a heterodyne interferometer without frequency mixing are presented, which can be conveniently applied to achieve precision measurements of linear displacement, pitch, yaw and roll error of a precision linear stage by rearrangement of the optical parts of the interferometer. This research will provide a novel resolution for the application of the heterodyne interferometry in the precision measuring of six DOF.

多自由度几何误差高精度测量是精密机械制造、检测以及仪器仪表等行业共同关注的问题，也是目前未能很好解决的测量难题之一。激光外差干涉仪特别是差分平面镜干涉仪因具有高光学分辨率、最小光学死程、良好的环境扰动抑制能力等优点，在高精度几何测量中有巨大的潜力。而实际应用时，由于测量系统存在各种非理想因素，导致频率混叠，使被测信号中出现一个幅值可达几个纳米的非线性误差，成为影响测量精度的重要误差源。本申请围绕高精密位移台多自由度高精度测量这个目标，通过对多自由度误差差分平面镜干涉测量原理的研究，建立多自由度测量的数学模型；通过外差干涉非线性误差理论的研究，设计一种无频率混叠的外差干涉激光源、外差干涉结构，从根本上抑制非线性误差的产生；设计合理的误差传感器件，通过组件不同配置，实现位移台定位、偏摆、俯仰和滚转角的高精度外差干涉测量。本研究为实现激光全自由度高精度外差干涉测量提供一种新的解决方案。

多自由度几何误差高精度测量是精密机械制造、检测以及仪器仪表等行业共同关注的问题，也是目前未能很好解决的测量难题之一。本项目围绕高精密位移台多自由度高精度测量的目标，利用激光外差干涉特别是差分平面镜干涉仪所具有高光学分辨率、最小光学死程、良好的环境扰动抑制能力等优点，设计了一种无频率混叠的外差干涉结构，从根本上抑制非线性误差的产生。通过外差干涉非线性误差理论的研究结合实验，确定了所设计的外差干涉仪能有效抑制非线性误差，将系统误差控制在亚纳米级；设计了一种偏振分光置换器，改善了光路结构，使干涉仪具有完全对称、共光路的特点，有利于提高系统抗干扰能。建立了多自由度误差测量的数学模型，通过不同组件配置来实现多自由度几何误差的高精度外差干涉测量。本项目的理论和实验结果为实现激光全自由度高精度外差干涉测量提供一种参考，故具有一定的理论意义和潜在的工程应用价值。