共光路外差干涉仪具有很高的分辨率,但因为安装、调试误差会产生非线性误差,影响系统的测量精度。着重分析了在共光路外差干涉仪中由激光光源的椭圆偏振化和沃拉斯顿棱镜的安装方位角误差同时存在的情况下,引起的频率混叠综合误差的大小及变化规律。结果发现其造成的非线性误差可达2.2 nm,同时还发现两者造成的误差在某些情况下存在一定程度的相互抵消作用。讨论了提高测量系统精度的有效措施, 对正确设计和调试激光外差测试系统、提高测量系统精度具有重要意义。

Nonlinear errors caused by mis-installation of common-path heterodyne interferometer affected the measurement precision of the system. Frequency mixing errors caused by the two factors existing at same time, which are elliptic polarization of laser source and installation azimuthal error of Wollaston prism, were analyzed especially in common path heterodyne interferometer. It was found that the nonlinear error is up to 2.2 nm and the error caused by the two factors may be counteracted each other a certain extent on some condition. The magnitude of error and the way of changing were given, which are of great importance in improving the measurement accuracy in common-path heterodyne interferometry. To the above basis, procedures to improve the accuracy of the measured system were suggested.