Mfr. of ophthalmic lenses at reduced cost - using composite glass to eliminate grinding and polishing of one face

摘要

Glass product having at least on finished surface of ophthalmic quality, is mfrd. by (a) forming a first layer (I) of a suitable glass having at least the desired length, width and thickness of the product; (b) coating layer (I) with a second relatively thin layer (II) of glass which can be removed at one stage later in the process; (c) fusing (I) and (II) to form a black; (d) flattening the blank to obtain an ophthalmic surface on (I) adjacent to (II); (e) softening and forming to shape; (f) removing layer (II) to expose the ophthalmic surface obtd. on layer (I) by stages (d,e). The layers are pref. produced by a float process and layer (II) removed by chemical soln. Blanks can be produced with at least one finished surface protected by layer (II) so no more than one surface requires grinding and polishing to make a finished lens.