Polaroid Corporation

Igor Loshak

William H Dalzell

Nancy J Gettens

Carole L McCarthy

A thermoformed plastic laminar light-polarizing composite lens blank is produced from a laminate comprising a light-polarizing layer between polymeric layers. The absorption axis of the light-polarizing layer of the laminate is aligned to substantial parallelism with a principal index of refraction of the polymeric layer which forms the convex surface of the lens blank and which is birefringent, thereby to minimize retardation effects of the birefringent material on plane polarized light. The polymeric layer which forms the concave surface of the lens blank is substantially thicker than the opposed polymeric layer in order to accommodate grinding of the surface thereof to an ophthalmic prescription. Thermoforming of unitary portions cut from a supply of the laminate is performed under heat and pressure.

Optical lens blank with polarizer aligned between plastic birefringent

A thermoformed plastic laminar light-polarizing composite lens blank is produced from a laminate including light-polarizing layer between polymeric layers. At least one of the polymeric layers is an optically isotropic sheet, i.e., a sheet having an optical retardance of 20 nanometers in order to minimize retardation effects of the birefringent material on plane polarized light. The isotropic layer or subsequent thermoforming of unitary portions cut from the laminate provides the convex lens surface of the lens blank. The polymeric layer which forms the concave surface of the lens blank is substantially thicker than the opposed polymeric layer in order to accommodate grinding of the surface thereof to an ophthalmic prescription. Lens blanks are prepared from unitary portions which are cut from a supply of the laminate, placed between thermoforming platens and formed under heat and pressure. By using a series of platens of different radius of curvature, for the forming of the convex surface of the lens blanks, a series or family of lens blanks can be provided to accommodate the grinding of lens to a variety of ophthalmic prescriptions.

Laminar light-polarizing lens blank for producing prescription lens

Plastic lenses having substantially no optical power and a light-polarizing layer therein are prepared by shaping composite laminate of the light-polarizing layer between opposed sheets of thermoplastic material by heating and pressing the laminate between opposed shaping molds (platens), the platens having predetermined radii of curvature for the production of a lens having substantially no optical power. Shaping is effected under conditions of heating and pressing sufficient to cause flow of the thermoplastic sheets and conformation thereof to the respective curvatures of the forming surfaces of the platens. The lenses are especially suited as sunglass lenses for spectacles.

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Cambridge, MA, United States of America

Igor Loshak