Closed-loop laser polishing using in-process surface finish metrology

This paper lays out the trail onto a closed-loop polishing process of optical elements enabling the application of the optimum polishing time needed. To that aim, an in-process testing method for monitoring an inclusive micro-surface quality (e.g., comprising surface roughness and scratch-and-dig) within the polishing spot is analyzed, and its applicability to closed-loop polishing for classical loose-abrasive full-aperture polishing as well as for computer-controlled laser polishing is experimentally tested and verified. This enables the determination of the optimum local dwell time resulting in stable and cost-optimized polishing.