Solving surface parameters of conic asphere mirror based on computer simulation

Abstract

Radius of curvature R and conic constant k are important parameters of aspheres.Null testing or CGH are usually used to evaluate the processing quality of aspheric mirrors in fabricating process . When the null compensator emerges a problem, additional method to ensure the accuracy of paraxial radius of curvature and conic constant is required. Based on the equation of conic aspheric, the computing model from which the paraxial radius of curvature R and conic constant k can be obtained was established, and a set of solving algorithm using singular value decomposition (SVD) method was derived. The simulating result of a 1800mm aspheric mirror is presented and the solving precision reaches R=6120±0.026mm, k=-1.0194±0.0008, thus the supplement to null testing of aspheric mirror is achieved effectively .