Method for manufacturing an injection molded thermoplastic ophthalmic lens having an encapsulated light polarizing element

Abstract

A method for manufacturing a synthetic resin thermoplastic ophthalmic lens by injecting a thermoplastic material immediately adjacent to each side of a light polarizing wafer situated within a mold cavity. The light polarizing wafer includes tab appendages which are positionable into registration notches in the mold cavity in order to maintain the wafer in a desired position in the mold during lens formation. The thermoplastic material is then injected around the light polarizing wafer, whereupon a compression procedure is implemented where the contents of the mold cavity are compressed. The mold cavity is compressed to a predetermined position to achieve a desired shape of the lens. Uniform compression is exerted over the entire surface of lens during the compression procedure, resulting in all stresses being uniformly distributed over the lens surface to significantly negate stress-inducted birefringence in the formed ophthalmic lens.

Dependencies are inferred from the claim text.