平行平板横向剪切干涉仪装调误差的矫正方法研究

Correction Methods of Adjustment Errors for the Parallel Plate-based Lateral-shearing Interferometer

对平行平板双光路横向剪切干涉仪的装调进行了研究,提出了一种矫正两个平行平板之间角度误差的方法.输出激光的波前采用Zernike多项式拟合,经过理论推导,发现两个方向差分波前求解出的倾斜像散之差与平行平板的角度误差存在线性关系,利用两个方向倾斜像散之差来矫正两个平行平板之间的角度误差.在平行平板横向剪切干涉仪的装调过程中使两个方向差分波前的倾斜像散之差为零即可以使两个方向的平行平板之间的角度误差值为零.进一步地从实验上证明了这个线性关系,对于所用的实验系统,当离焦像差为-3.224 7±0.001 8,两个方向差分波前的倾斜像散之差波动范围为±2.0×10^-3时,平行平板的角度误差可以控制在8.82″之内,高阶像差对平行平板的角度误差调节精度的影响约为1.63″.该方法具有装调简单、精确度高,易于流程化操作的优点.

The adjustment of the parallel plate dual-path lateral-shearing interferometer was investigated and a method to correct the angle error of the parallel plate was proposed.The wavefront of the laser is fitted with the Zernike polynomial.Based on theoretical derivation,it is found that the difference between oblique astigmatism of wavefront in two directions has a linear relationship with the angle error of the parallel plate.Therefore,the difference between oblique astigmatism of wavefront in two directions can be used as a feedback to adjust the angle error of the parallel plate.The angle error of two parallel plates can approach zero by making the difference between oblique astigmatism of wavefront in two directions is equal to zero during adjusting the parallel plate lateral-shearing interferometer.The linear relationship was further proved by experiments.When defocus aberration is-3.224 7±0.001 8 and the fluctuation range of the difference between oblique astigmatism of wavefront in two directionsis±2.0×10^-3,the experimental angle error of two parallel plates for our experimental system can be controlled within 8.82″.The effect of higher-order aberrations on the accuracy of angle error adjustment is approximately 1.63″.This method has the advantages of easy adjustment,high accuracy,and easy process operation.