Stitching optimization for large-aperture aspheric surface and accuracy testing

An optimization algorithm based on stitching for two segments of surface figure is proposed to solve the problem that the stitching measuring of lare-aperture asphere lacks accuracy during grinding process. Firstly, the preliminary stitching model for two segments of surface profile is built. Secondly, the effect of motion ( and L) and motion error ( and L) are analysed using 350 mm workpiece stitch simulation. Simulation results indicate stitching errors increase as translation errors increase and the standard deviations of stitching errors are 0.2 m when translation is under 10 mm, and the rotation is under 8, and the rotation error is under 60 and the translation error is under 3 m. Finally, Talysurf PGI 1240 and stitching fixture are used to test 120 mm aspheric optical element and analyse the effect of different motion. Experimental results indicate the standard deviations of stitching errors are 0.2-0.6 m when translation is under 10 mm and the rotation is under 8. It can satisfy the measuring requirements of surface profile in optical elements during grinding process.