Surface Shape Detection Of Off-axis Aspheric Surface Based On Reverse Iteration Method

In optical systems,if only a spherical optical element is used,the element can only provide the radius of spherical curvature as an optimization term.Compared with the aspheric surface,the off-axis aspheric surface also has off-axis quantity and aperture limit,and it has more flexible design freedom.If applied in the optical system,the imaging quality can be better improved and the system structure can be simplified.At present,the main reason that restricts the large-scale application of off-axis aspheric surface is the development of detection means,especially the development of high-precision detection means.Due to the special structure of off-axis aspheric surface,the compensation lens of special structure is mostly used in the detection system,and these compensation systems correspond to the off-axis aspheric surface to be tested,so the detection period is long and the universality is poor.In this paper,a compensation system is studied without the need to design a specific compensation system.We only need to use the existing standard lens to build a detection optical path and obtain the wavefront of the system.Through the reverse iteration algorithm,the final wavefront of the detection is demodulated and the shape information of the measured off-axis aspheric surface is obtained.This method not only can effectively detect the surface shape information of the off-axis aspheric surface,but also has strong universality and low detection cost in the detection of off-axis aspheric surface.The main content of this paper is as follows: the current situation of off-axis aspheric surface detection is described,especially the most commonly used zero and non-zero detection methods,and the necessity of reverse iteration of off-axis aspheric surface shape is explained.A backward iterative algorithm based on zernike extension theory is proposed by introducing zernike extension theory,which solves the surface shape fitting problem in quadratic and high-order off-axis aspheric surface detection.Through the simulation analysis,the errors in the final detection wavefront and the processing methods of these errors are analyzed.Finally,an off-axis aspheric surface detection system is designed,a detection platform is built,the collected interference patterns are analyzed and processed,and the surface shape of the off-axis aspheric surface is finally obtained.The feasibility of reverse-iterating the off-axis aspheric surface shape was verified by comparing with the CGH detection results from the institute of optoelectronics of Chinese academy of sciences.