Calibration and optimization of computer-controlled optical surfacing for large optics

Precision optical surfaces can be efficiently manufactured using a computer-controlled optical surfacing (CCOS) process. Most CCOS processes are based on control of the dwell time of a tool on the workpiece, according to the desired removal and the tool influence function (TIF), which is the material wear function of the tool. Several major topics were investigated to improve current CCOS processes and provide new solutions for the next generation of CCOS processes. A rigid conformal (RC) lap using a visco-elastic non-Newtonian medium was invented. It conforms to the aspheric surface shape, yet maintains stiffness on short time scales to provide natural smoothing. The smoothing removes mid- to high-frequency errors while controlled dwell time removes low-frequency errors. A parametric smoothing model was also introduced to predict the smoothing effects. A parametric edge TIF model to represent measured edge TIFs was developed and demonstrated. This model covers the removal behavior as the tool overhangs the edge of the workpiece. These new tools and models were applied in a new process optimization technique called nonsequential optimization. The non-sequential approach performs a comprehensive optimization of dwell time using multiple TIFs (multiple tools) simultaneously. An overview of these newly implemented CCOS features** is presented along with some actual CCOS results.