Method for figure correction of optical element by reactive ion etching

Abstract

A method for figure correction of an optical element includes forming a masking layer on a surface of the optical element. The optical element has thinning regions and non-thinning regions. The masking layer is patterned to form masking regions and non-masking regions, and the masking layer is positioned relative to the optical element in such a manner that the masking regions corresponds to the non-thinning regions of the optical element and the non-masking regions corresponds to the thinning regions of the optical element. The method further includes performing reactive ion etching on the optical element provided with the masking layer so as to etch the thinning regions of the optical element to reduce a thickness of the thinning region.

Dependencies are inferred from the claim text.