Study on computer-aided alignment method of a three-mirror off-axis aspherical optical system

Abstract

The precise alignment of multiple element off-axis optical system is a challenging task. In order to increase the alignment process efficiency, computer-aided alignment methods utilizing Zernike polynomial coefficients have been developed. In this paper, the misalignment state of three-mirror off-axis optical system is simulated in CODEV and computer-aided alignment software. The corresponding relationship between the misalignment and Zernike polynomial coefficients is analyzed, Finally, the alignment scheme is determined by the above analysis. In order to verify the feasibility, by using inverse optimization method to join the different disorders analysis of come up with the ways of solving the optimization variables, based on the established computer-aided alignment model to calculate misalignment. The off-axis three-mirror telescope was aligned by measuring the wave-front error (WFE) in several fields, namely, obtain Zernike polynomial, then using the self-compiled computer-aided alignment software to calculate the value and direction of misalignment, this method is realized by optimizing adjustment to compensate for the other variables misalignment-related variables. It can meet the precision requirement and accelerate the convergence of misalignment variables. With variables deduced, the time of alignment is saved. At a wavelength of 632.8nm, the results of 0°field wave-front error of 0.060λ rms, +3°field of 0.076λ rms and -3°field of 0.073; rms are obtained. The quality factor is better than 0.85.