US 5,219,497 A · Method for manufacturing lenses using thin coatings

Abstract

A fast, relatively inexpensive and simple method for producing a finished plastic aspheric multifocal or progressive lens from a preformed lens which has a predetermined lens correction (i.e., curvature or prescription) at its optical center. The method includes providing a mold; providing an optical photoactivated resin composition; providing a preformed plastic lens; contacting the preformed lens with the mold such that the surfaces of the preformed lens and the mold form a cavity enclosing the resin composition; and curing the resin composition upon application of heat and ultraviolet radiation. The cavity formed by the preformed lens and the mold is shaped to correspond to the desired change in curvature of the mold surface. The preformed lens may also be cast with a thin non-prescription layer which acts as a carrier for the multifocal or progressive region of the finished lens. This allows casting of lenses without employing either expensive conventional optical gaskets or back molds. The methods also allow for simpler relocation of the optical center to the proper position with respect to the multifocal or progressive prescription, without using conventional optical gaskets.

Claims24

Dependent claims

A method for manufacturing lens blanks comprising:

molding semi-finished lens blanks having a bonding surface of optical quality and a rear surface for grinding and polishing in a subsequent step;
said bonding surface having a known curvature;
providing a mold having a molding surface;
providing an optical quality resin composition containing an initiator activated by ultraviolet radiation, said resin composition being substantially free of thermal initiators;
providing a preformed lens backing having a lens bonding surface and a rear surface for grinding and polishing;
arranging said lens backing with said mold such that the bonding surface of said lens backing and said mold form a cavity enclosing said resin composition;
said cavity having a relatively thin space throughout and cooperating with said lens backing to form an outer surface of optical quality;
placing said resin in said cavity such that said resin has an unequal thickness between said mold and said lens backing;
curing said resin composition by applying ultraviolet radiation and heat to said resin composition, wherein said resin is cured while remaining substantially free of thermal initiators, and wherein said heat is provided in a controlled manner to equalize the degree of cure over portions of the resin having unequal thickness;
wherein the lens surface curvature of resulting lens is of substantially the same curvature as the mold used and grinding said rear portion of said lens blank and polishing said rear surface to arrive at a lens of a desired power.

7 more elements

A method for making a finished lens having an aspheric, multifocal or progressive region, said method comprising:

a. providing a mold having a molding surface;
b. providing an optical quality resin composition containing an initiator activated by ultraviolet radiation, said resin composition being substantially free of thermal initiators;
c. providing a pre-formed plastic lens having a bonding surface;
d. said mold having a first complementary surface of a curvature different than that of the bonding surface on the preformed lens and a second surface corresponding to an aspheric, multifocal or progressive region to be added;
e. said aspheric, multifocal or progressive region constituting a portion of the mold;
placing said resin composition in said mold, arranging said preformed lens with said mold such that the bonding surface in said preformed lens and said mold form a cavity enclosing said resin composition, such that said resin has an unequal thickness between said mold and said preformed lens;
f. said cavity having a first portion cooperating with said mold to form a space therebetween of a changing thickness and a second portion cooperating with said mold to form said aspheric, multifocal or progressive region;
g. curing said resin composition by applying ultraviolet radiation and heat to said resin composition, wherein said resin is cured while remaining substantially free of thermal initiators, and wherein said heat is provided in a controlled manner to equalize the degree of cure over portions of the resin having unequal thickness;
and
h. wherein the added lens curvature of said resulting lens substantially corresponds to that of the molding surface of said mold.

7 more elements

Dependencies are inferred from the claim text.

Method for manufacturing lenses using thin coatings

Life of this patent

Method for manufacturing lenses using thin coatings

Life of this patent

Abstract

Claims24