大口径碳化硅反射镜数控抛光工艺

Polishing of large-aperture reflective SiC mirror using computer-controlled optical surfacing

研究了针对600mm口径方形轻质碳化硅元件的数控抛光工艺过程,采用国产OP1000数控研磨抛光机床对一块600mm×480mm的方形碳化硅元件进行数控抛光加工。在经过两周的加工时间,碳化硅光学元件的通光口径均方根(RMS)值收敛到了35nm(大约为λ/18,λ=632.8nm)。在加工过程中针对大口径椭圆形碳化硅反射镜采用了合适的加工参数优化,例如在加工过程中的不同阶段选择了不同颗粒度的金刚石微粉作为特定阶段的抛光辅料以保证光学元件的表面粗糙度。对计算机控制数控加工技术的快速收敛过程也进行了阐释。

A 600 mm aperture SiC flat mirror was polished up to an aperture of 35 nm （RMS） with computer-controlled op- tical surfacing （CCOS） in a very short period. The SiC mirror structure, the choose of the diamond powder, and other procedures in CCOS are presented in the paper. The adjustment of the removal function in the polishing process was carefully performed in order to increase the polishing efficiency of the silicon material, and the efficiency in PV and RMS convergence was obtained ac- cording to the experiment results. In addition, the efficiency in polishing SiC material needs to be further analyzed to make sure that the batch production of this kind of hard material mirror is possible.