非球面碳化硅表面硅改性层的数控化学机械抛光

Computer-controlled chemical mechanical polishing of silicon modification layer on aspheric silicon carbide surface

提出了一种数控化学机械抛光技术以实现非球面碳化硅表面硅改性层的高效精密抛光并获得高质量非球面碳化硅反射镜。研究了非球面碳化硅表面硅改性层的化学机械抛光机理,阐述了表面改性非球面碳化硅反射镜的数控化学机械抛光原理。通过与普通数控抛光对比,说明了数控化学机械抛光的优势。通过数控化学机械抛光实验,研究了这种抛光方法的材料去除函数。最后,以材料去除函数的研究结果为依据,采用数控化学机械抛光技术对口径为120mm表面改性非球面碳化硅反射镜进行抛光。经过几个抛光周期的迭代,表面改性非球面碳化硅反射镜的面形精度由0.253λ(RMS值)(λ=0.632 8μm)收敛到0.014λ(RMS值),反射镜的表面粗糙度达到0.538 7nm(RMS值),满足光学设计技术指标的要求。

A computer-controlled Chemical Mechanical Polishing（CMP） technology was presented to polish a silicon modification layer on the aspheric silicon carbide（SiC） surface in high precise and efficiency to achieve a high quality aspheric SiC mirror.The polishing theory of CMP for the silicon modification layer on aspheric SiC surface was studied.Then,the principle of computer-controlled CMP for manufacturing a surface modification aspheric SiC mirror was described.With comparing the computer-controlled CMP and ordinary computer-controlled polishing,the superiority of computer-controlled CMP was explained.Furthermore,on the basis of experiments,the material removal function of computer-controlled CMP was studied.Finally,a Φ120 mm surface modification aspheric silicon carbide mirror was polished by computer-controlled CMP technology according to the material removal function.The initial figure error of the mirror is 0.253λ（RMS）（λ=0.632 8 μm）.After about ten polishing iterations,the final figure error and roughness of the mirror are 0.014λ （RMS） and 0.538 7nm （RMS）,respectively,which can satisfy the desired optical performance.