激光外差干涉检偏器旋转误差对非线性误差的影响

Effect of Nonlinearity by the Rotation of the Polarizer in Laser Heterodyne Interferometric

为了减小激光外差干涉纳米测量的非线性误差,必须明确检偏器旋转误差对非线性误差的影响机理与消除方法。通过分析激光外差干涉检偏器旋转误差对非线性误差的影响,推导出检偏器旋转误差对非线性误差一次谐波和二次谐波的影响模型。仿真结果表明,当存在激光束椭圆偏振时,检偏器旋转误差对非线性误差的影响很小;当存在偏振分光镜旋转误差时,检偏器旋转误差引起的非线性误差不增加二次谐波分量,但增大了非线性误差一次谐波分量,严重影响非线性误差的大小,当偏振分光镜旋转误差为3°时,检偏器旋转误差从0°增加到5°,非线性误差从0.14 nm增大到0.97 nm。

To reduce the nonlinearity of nanometer measurement in laser heterodyne interferometric, the influence mechanics of the error of polarizer rotation angle upon nonlinearity and eliminating method must be confirmed. Based on the analysis of the influence on nonlinearity caused by the error of polarizer rotation angle, the models about how first harmonic and second-harmonic nonlinearity affected by the error of polarizer rotation angle have been proposed. The emulation result shows that the error of polarizer rotation angle almost does not influence nonlinearity when elliptic polarization of laser beams exists; when the error of rotation angle of polarizing beam splitter （PBS） exists, the second-harmonic nonlinearity caused by the error of polarizer rotation angle will not increase, but the first-harmonic nonlinearity will increase greatly, h is assumed that the error of rotation angle of PBS is 3°, nonlinearity will increase from 0. 14 nm to 0.97 nm when the error of polarizer rotation angle increases from 0°to 5°.