Optimized Selection of Merit Function in Computer-Aided Alignment of Precision Optical System

摘要

The proper application of computer-aided alignment technology can overcome blindness in the alignment process of precision optical system, and reduce the alignment cycle. In which, reasonable merit function of the system's imaging quality is the primary precondition of successful reverse-solving of misalignment. In this paper, firstly, the relation between misalignment and system wavefront aberration is established through mathematic modeling, and by detailed analysis of the relation between Zernike coefficients, geometric aberration and system imaging quality, the merit function of imaging quality based on weighted Zernike coefficients is proposed so as to avoid the numerical instability and inaccuracy of solution caused by direct adoption of Zernike coefficients. Finally, alignment experiment of one infrared optical system is carried out based on the merit function established, and the result shows that, using the same reverse-solving algorithm, compared with direct adoption of Zernike coefficients, weighted Zernike coefficients adopted as the merit function can improve the imaging quality RMS as much as 17%.