Fabrication of SiC Off-axis Aspheric Mirror by Using Robot Polishing

Two silicon carbide (SiC) lightweight off-axis aspheric mirrors were fabricated by using robot polishing technology. One is a primary mirror with dimension 380mm×328mm, the other is a tertiary mirror with dimension 294mm×238mm. The robot polishing technology is the combination of CCOS technology and a 6-axises industrial robot. The setup of robot polishing system is discussed, and the mirror aspheric grinding, surface polishing and figuring process are reported in this paper. The final surface shape error of primary mirror is 11.4nm RMS, and the tertiary is 12.1nm RMS. The capability of off-axis aspheric mirror fabricating on robot polishing system is verified.