衍射主镜面外拼接误差分析

Piston and Tip-Tilt Error Analysis of Segmented Diffractive Lens

多子镜拼接的方法可实现大口径菲涅耳衍射透镜制作,但拼接误差会对光学系统的成像质量造成影响。通过衍射光线追迹和波前恢复的方法,正向得到了子镜沿自身x′轴倾斜、y′轴倾斜、z′轴平移等面外误差与对应波前误差Zernike系数的数据库。利用数据库基于反向传播神经网络优化算法反向建立波前误差Zernike系数与对应面外误差的非线性耦合映射模型,可实现通过输入Zernike系数完成对面外误差耦合扰动情况的快速求解,运用带有符号的数值判定面外误差的大小及方向。对该模型进行模拟数值计算,验证了该方法的精度及可靠性,为衍射拼接主镜的共面检测、装调提供理论依据。

The large-caliber Fresnel diffraction lens can be produced by the multiple segmented lens splicing method,yet the splicing error has effects on the image quality of the optical system.The database of piston and tip-tilt error and corresponding wavefront error Zernike coefficient of the segmented lens along its own x′axis tilt,y′axis tilt,z′-axis piston is obtained by means of diffractive ray tracing and wavefront reconstruction method.The nonlinear coupling mapping model of the Zernike coefficient and the corresponding piston and tip-tilt error is established with the database based on back-propagation neural network optimization algorithm.We can accomplish the quick solution to the piston and tip-tilt error coupling disturbance by inputting the Zernike coefficients,and determine the magnitude and direction of the piston and tip-tilt error by the symbol of values.The model is simulated numerically,the accuracy and reliability of the analytical method are verified.This work provides theoretical basis for the coplanar detection and adjustment of the segmented diffractive lens.