Effect analysis of the residual error evaluation method used in bonnet polishing process for aspheric lens

The purpose of this paper is to investigate the effect of the residual error evaluation method used in bonnet polishing (BP) process to the axisymmetric aspheric surface accuracy. In the past, few attentions have been paid to the normal direction error (NE) of the aspheric surface, not to mention its application in BP. In this paper, a new approach is proposed to calculate NE on the basis of the axis direction error (AE) of the aspheric surface. The comparison of them is presented through a group of experiments on four asxisym-metric aspheric lenses. The effect of using AE as the residual error in BP process to the final surface accuracy is tested. It is confirmed that it would result in the difference between the practical final surface form and the theoretical final surface form, and NE should be used as the residual error in BP process.