Super Polished Fused Silica and Fused Quartz
Wafers, substrates and optical windows now can be super-polished to have a 3 - 4 Angstrom Ra surface finish.
The surface finish of a polished fused silica wafer can be improved by repolishing to reach 3 - 4 Angstrom Ra superpolished smoothness. If the polished surfaces have been compromised during processing, these surfaces also can be improved by repolishing to 3 - 4 Angstrom level with minimal stock removal.
Standard polish on Fused Silica with 5.1 to 6.7 Angstrom Ra surface finish - prior to superpolishing.
WYKO Scan of a Super-Polished Surface with 3.4 to 3.9 Angstrom Ra surface finish.