平面子孔径拼接测量实验研究

通过椭圆形口径（长轴225mm，短轴161mm）SiC平面反射镜的全口径面形测量加工实验，验证了一种新的子孔径拼接测量算法—子孔径拼接迭代算法（SASL算法）的有效性。首先用100mm口径平面平晶的子孔径拼接测量与全口径测量的对比实验，确定了拼接测量相关参数及测量装置的精度指标。在此基础上设计了SiC平面反射镜的子孔径拼接实验，在搭建的拼接装置上实现了五次离子束迭代加工过程中和最终的全口径面形测量。这是国内首次将子孔径拼接测量方法用于指导加工实践，加工过程中的测量结果为面形误差修正提供了准确的数据，保证了最终全口径面形误差快速收敛到RMS 50nm。实验证明，SASL算法能大大放宽拼接装置对准运动的精度要求，并减少拼接过程对拼接结果的影响。

Experimental study on subaperture stitching interferometry of flat mirrors

For the purpose of validating a new stitching algorithm—Sub-aperture Stitching and Localization (SASL) algorithm,a measuring and figuring experiment was described for the SiC flat mirror with elliptical shape of 225 mm in major axis and 161 mm in minor axis.A comparative experiment of sub-aperture stitching test with full-aperture interferometry on a 100 mm diameter flat mirror was presented in order to determine the algorithm parameters and the precision requirement of stitching equipment.Following this,a sub-aperture stitching process for the SiC flat mirror was carried out,which contained 5 iterations of Ion Beam Figuring (IBF) process and a full-aperture testing.In this process,sub-aperture stitching test offered the surface error data precisely to IBF,which ensured the quick convergence for the process to achieve a final surface RMS error of 50 nm.The experimental results show that SASL algorithm relaxes the precision requirement for the stitching equipment and reduces the influence of stitching process on the results.