针对以往文献提出的探测非线性误差方案比较复杂,通常不容易实行的缺点,设计了一套简单有效的系统,用以区分由光源偏振态非理想和偏振分光镜(PBS)漏光引起混频造成的非线性误差.实验结果表明,光先后两次经过PBS后漏光分量将会大大减少,相对于由光源非正交分量引起的混频误差可以忽略不计.为了最大限度地减小安装误差,提出了一种切实有效地调整PBS的方法,确保入射光水平分量的偏振面平行于偏振分光镜的参照面,并以布儒斯特角入射.

It is difficult to detect nonlinearity of heterodyne interferometer,a simple system is proposed which can distinguish the frequency mixing led by non-ideal laser source and the leakage of polarizing beam splitter(PBS).The experimental result shows that the frequency mixing due to the leakage of PBS can be generally neglected because the leakage of PBS mostly is filtered after through PBS twice. A method to adjust PBS is proposed,the beam incident at Brewster angle and the polarization plane of horizontal component paralleling to the reference plane of PBS are ensured,it can minimize the influence of fix-errors.