Preparation of photochromic gradient lenses of cosmetically impr

Details Preparation of photochromic gradient lenses of cosmetically impr Preparation of photochromic gradient lenses of cosmetically impr

1976-03-18

1978-03-21

Sacher, Paul A.

Optics: eye examining, vision testing and correcting

Spectacles and eyeglasses

Ophthalmic lenses or blanks

65DIG2, 106 47Q, 106 52, 106 54, 106DIG6, 350354, G02C 710, G02B 523

Patent

active

040800512

ABSTRACT:
Glass lenses, or lens blanks, containing all the ingredients necessary to produce phototropic, or photochromic, behavior, are treated in a conventional production furnace to produce a locally variable heat treatment, wherein at least one portion thereof is raised to a temperature exceeding the glass strain point but not the softening point, and other portions are heated to variable temperature decreasing from the strain point. The treatment causes development of phototropic, or photochromic, behavior only in those portions of the lenses, or lens blanks, exposed to the temperature above the strain point. The lenses resulting are characterized by trichromatic coefficients, x=0.306 and y=0.307, in the unactivated state and x=0.324 and y=0.321, in an activated state and including a small but effective quantity of cobalt oxide.

REFERENCES:
patent: 2675740 (1954-04-01), Barkley
patent: 3197296 (1965-07-01), Eppler et al.
patent: 3208860 (1965-09-01), Armistead et al.
patent: 3255026 (1966-06-01), Stroud
patent: 3419370 (1968-12-01), Cramer et al.
patent: 3892582 (1975-07-01), Simms
patent: 3920463 (1975-11-01), Simms
patent: 3957499 (1976-05-01), De Munn et al.
"Photogray Glass for Ophthalmic Lenses", Corning Tech. Bulletin, July 1970, 8 pp. & cover.

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