Spectacle lens with spherical front side and multifocal back side and process for its production

Abstract

A spectacle lens has a spherical or rotationally symmetrical, aspheric front side and a back side prescription surface. All individual requirements of the prescription for spectacles, consisting of spherical, astigmatic and prismatic power and their distribution on the x and y axes on the spectacle lens surface, are fulfilled by the prescription surface. The back surface of the spectacle lens is a multifocal surface without point symmetry and/or axial symmetry. A process that produces spectacle lenses with multifocal power starts with variants of a first or of a few spectacle lens(es) that originate according to prior art design considerations. The semi-finished lenses have spherical or aspheric, rotationally symmetrical, convex front surfaces, with about 10 different radii. The whole matching of individual required dioptric power takes place on a free-form back surface of the spectacle lens facing the eye of the wearer. The shape of this back surface follows from an individual optimization calculation using the design of the predefined starting surface as the start of the optimization.

Dependencies are inferred from the claim text.