Apparatus and process for producing a gradient photochromic ophthalmic lens
AssigneeCorning Glass Works
InventorEdwin J. Illig
Life of this patent
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Abstract
A gradient photochromic ophthalmic lens blank is produced by heat treating an ophthalmic lens blank composed of potentially photochromic glass at a temperature sufficient to develop photochromic properties therein, while maintaining in proximity to a portion of the lens blank a metal heat sink with a specified heat absorbing capacity. The metal heat sink acts to provide a temperature gradient across the ophthalmic lens blank during heating, which gradient is effective to provide a gradient in photochromic properties thereacross.
Claims4
A process for manufacturing a gradient photochromic ophthalmic lens blank which comprises the steps of:
- (a) subjecting an ophthalmic lens blank composed of a potentially photochromic glass to a heat treatment at a temperature sufficient to develop photochromic properties in said glass, while
- (b) maintaining a selected portion of the ophthalmic lens blank in proximity to a solid metal heat sink having a heat capacity of at least about 15 calories .degree. C.sup.-1 ;
- said metal heat sink acting to provide a temperature gradient across the ophthalmic lens blank which is effective to provide a gradient in photochromic properties thereacross.
Lens treating apparatus for producing a gradient photochromic ophthalmic lens blank which comprises:
- (a) a cylindrical open-bottomed step-ring former cup, said former cup having a circular wall which includes a circumferential step therein;
- (b) a ceramic former positioned within the step-ring former cup and edge-supported by the circumferential step, said ceramic former being suitable for supporting a potentially photochromic ophthalmic lens blank;
- (c) a cast iron heat sink of semicircular cross-section positioned against the circular wall of the former cup and immediately beneath the ceramic former, said cast iron heat sink having a heat capacity of at least 15 calories .degree. C.sup.-1.
Dependencies are inferred from the claim text.