Research on stitching measurement technology for large aspheric optics during grinding process

大口径非球面光学元件能校准像差，提高像质，减小光学系统的体积和重量，并增加光学系统的可靠性，因此其被广泛应用于航空航天、国防等先端科研技术领域。磨削阶段大口径非球面元件的面形检测是制约其推广应用的重要因素。坐标测量技术是实现磨削阶段光学元件面形检测的重要手段，但是该技术在解决大口径、高陡度非球面元件的高精度测量上仍存在一系列技术问题需要解决，比如自主开发的轮廓仪因成本高昂大多难以推广，轮廓仪测头传感器有效测量行程不足，待测工件的大尺寸相比轮廓仪运动量程受限，多段拼接方法测量效率与精度不足且无法实现对非球面三维面形的测量等。针对上述问题，本文对基于商用式小量程高精度轮廓仪的磨削阶段大口径非球面光...Large aspheric optical elements are extensively applied in aerospace and military field, because large aspheric optics can calibrate aberrations, improve image quality, reduce the volume and weight of the optical system, and increase the reliability of the optical system. The surface measurement of large aspheric optics during the grinding process is a key influence factor for its application. The...学位：工学硕士院系专业：航空航天学院_机械电子工程学号：1992013115289

Stitching Measurement Technique for Large-aperture Aspheric Surface during Grinding Process

为实现对磨削加工阶段大口径非球面光学元件的精密测量,提出一种基于坐标测量的多段拼接综合优化数据处理模型。基于多体系统理论、最小二乘原理建立两段面形轮廓拼接数学模型;提出基于曲率原理和非球面方程最小二乘拟合的冗余数据剔除数学模型;建立多段拼接的综合优化处理模型;利用TAylOr HObSOn轮廓仪对口径为176 MM的非轴对称非球面光学元件的3条母线进行分段测量试验并通过文中提出的数学模型进行数据拼接处理,试验结果表明,拼接测量结果与单次测量结果相比,误差最大值的平均值为0.25μM,最小值的平均值为–0.22μM,比该光学元件的面形峰-谷值2.77μM高出一个数量级,达到检测要求。试验结果证明所提多段拼接综合优化数据处理模型的正确性及有效性,该模型可以进行工程应用。In order to test large-aperture aspheric surface optice element accurately during grinding process, a comprehensive optimization data processing model of stitching measurement is proposed based on coordinate measuring.Firstly, the stitching model for two segments of surface shape contour is built based on multi-body system theory and least square principle; secondly, the rejecting redundant data model is built based on curvature principle and least square fitting of aspheric equation; then the comprehensive optimization processing model for multiple segments stitching is built; three generatrices of a non-axisymmetry aspherical optical element whose aperture is 176 mm is stitching measured by Taylor Hobson profilometer and the data is processed by the model mentioned in the text.The results show that the maximum average error of the stitching measurement is 0.25 μm, and the minimum average error of the stitching measurement is –0.22 μm which is compared with the single measurement.The error is an order of magnitude higher than the surface shape peak–valley value 2.77 μm of the optic element, and matches the measurement requirements.The experimental results prove the correctness and effectiveness of the comprehensive optimization data processing model of stitching measurement, and the model can be applied in engineering.国家自然科学基金资助项目(51075343;51275433

Stitching optimization for large-aperture aspheric surface and accuracy testing

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350MM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10MM以内、旋转误差在60′以下及平移误差在3μM以下时,拼接误差的标准偏差值在0.2μM波动;最后利用TAylOr HObSOn轮廓仪和高精度辅助测量夹具对120MM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10MM以内和旋转角度在8°以下时,拼接误差的标准偏差值在0.2~0.6μM之间,能满足磨削阶段光学元件亚μM级精度的面形检测要求。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(αand L)and motion error(ΔαandΔL)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 0.2μm 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 3μm.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 0.2-0.6μm 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.国家科技重大专项资助项目(2013ZX04006011-206