Stitching optimization for large-aperture aspheric surface and accuracy testing
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摘要: 针对磨削阶段大口径光学非球面元件拼接测量精度不高的问题，提出一种基于两段拼接的优化算法。首先根据多体系统运动学理论、斜率差值及逆推法建立两段面形轮廓的拼接数学模型；其次针对拼接算法中工件运动量和运动误差对拼接精度的影响，仿真分析了350 mm非球面工件的两段拼接。仿真结果表明，随着平移误差增大，拼接误差明显增大，而当控制旋转角度在8以内、平移量在10 mm以内、旋转误差在60以下及平移误差在3 m以下时，拼接误差的标准偏差值在0.2 m波动；最后利用Taylor Hobson轮廓仪和高精度辅助测量夹具对120 mm口径的非球面光学元件进行测量实验并研究工件运动量对拼接测量精度的影响。实验结果表明，当控制平移量在10 mm以内和旋转角度在8以下时，拼接误差的标准偏差值在0.2~0.6 m之间，能满足磨削阶段光学元件亚m级精度的面形检测要求。Abstract: 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.
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Key words:
- profile measuring /
- stitching of two segments /
- workpiece motion /
- motion error
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