针对大口径离轴非球面系统加工与装调的难点, 提出了非球面光学系统共基准加工与检测的方法, 对该方法的基本原理和实现过程进行了分析和研究。当光学系统的主镜和第三镜面形的RMS值优于λ/10(λ=632.8 nm)时, 对主镜和第三镜进行共基准装调和测试, 并进行背板一体化装嵌, 然后利用离子束对其进行一体化共基准加工。结合工程实例, 对一大口径非球面系统口径为724 mm×247 mm的非球面主镜和口径为632 mm×205 mm的第三镜进行了共基准加工与检测, 最终利用离子束共基准一体化精抛光得到主镜和第三镜面形的RMS值分别为0.019λ和0.017λ, 满足光学成像。

A key technology for fabricating and testing three mirror astigmatism (TMA) was proposed based on a common reference, to overcome the difficulty of manufacturing and aligning large off-axis aspheric systems. The analysis and research of the basic principles involved were presented. When the Root Mean Square (RMS) of the surface error of the primary mirror and tertiary mirrors was better than λ/10 (for wavelength λ at 632.8 nm), the primary and tertiary mirrors were measured and aligned with the common reference and the same supporting back plate, with the two mirrors were then being polished by Ion Beam Figuring (IBF). A large TMA system with primary and tertiary mirror apertures of 724 mm×247 mm and 632 mm×205 mm, respectively was fabricated and tested based on the proposed method. The integrated mirrors were polished by IBF, and the RMSs of the surface error of the primary and tertiary mirrors are 0.019λ and 0.017λ, respectively.