COLLOIDAL SILICA FINISHING OF METAL FLUORIDE OPTICAL COMPONENTS

摘要

The invention is directed to a method for finishing alkaline earth metal fluoride optical components and to the alkaline earth optical elements produced using the method. In particular, in the last polishing step, the method of the invention uses a colloidal silica polishing slurry having containing silica particles having a particle size of <500 nm. Additionally, after colloidal silica polishing, the method using a megasonic cleaning step with a high pH detergent cleaning solution to remove any silica residue on the polished optical component. The optic resulting from use of the method has a polished and unetched surface roughness of less than 0.5 nm; a surface roughness of less then 0.6 nm after polishing and etching; and a step height of less than 6 nm.