Optical Polishing of Metals for Best Finish and Flatness
Optical metal polishing of flat surfaces can yield finishes in the 10 to 20 Angstrom Ra range depending on the alloy and the quality of the alloy.
Optically polished mirror surfaces on Aluminum typically range from 20 to 30 Angstroms Ra. Under ideal conditions Valley has achieved 8 Angstrom Ra surface finish on 6061T6 aluminum, but in general the surface finish attainable depends on many variables including material quality, part size, shape and thickness.
Optically superpolished fused silica wafers with 3 Angstrom Ra surface finish are being done at production level quantities. This level of surface finish is usually a requirement for critical MEMS surfaces.