为了减小外差干涉仪的非线性误差,必须明确波片和偏振片对非线性误差的影响机理。通过理论分析和试验发现,波片和偏振片位于偏振分光镜之前和之后对非线性的影响是不同的。如果把有误差的波片和偏振片放置在偏振分光镜前面,其误差将100%地引入非线性。如果将相同的这些光学元件安装在干涉仪里面,有可能影响非线性,但通常在高阶误差范围内。

To reduce the nonlinearity error of heterodyne interferometer,the influence mechanics of wave plate and polarizer upon nonlinearity error must be determined.Theoretical and experimental analysis showed that different influence on non-linearity exits when wave plate and polarizer were placed in the front of or behind the polarized beam splitter.If the error wave plate and polarizer were placed in front of the polarization beam splitter,non-linearity was introduced definitely due to error.If the same optical components are installed inside the interferometer,it is possible to affect the nonlinearity,but usually with a factor in an order of about 10^-2.