Ophthalmic glasses with high indices of refraction

Details Ophthalmic glasses with high indices of refraction Ophthalmic glasses with high indices of refraction

1981-12-07

1982-09-28

Bell, M. L.

Compositions: ceramic

Ceramic compositions

Glass compositions, compositions containing glass other than...

501903, C03C 310

Patent

active

043519067

ABSTRACT:
The present invention is drawn to glasses suitable for the fabrication of segments or buttons for multifocal ophthalmic lenses. The inventive glasses have refractive indices ranging between about 1.745-1.771, an Abbe number greater than 29 for a refractive index of 1.771 and greater than 31 for a refractive index of 1.745, a softening point between about 640.degree.-700.degree. C., a coefficient of thermal expansion (25.degree.-300.degree. C.) between about 90-98.times.10.sup.-7 /.degree.C., and satisfactory chemical durability. The glasses consist essentially, expressed in terms of weight percent on the oxide basis, of

REFERENCES:
patent: 3902910 (1975-09-01), Hares et al.
patent: 3973976 (1976-08-01), Boyd
patent: 4211569 (1980-07-01), Hares et al.
patent: 4213787 (1980-07-01), Faulstich et al.

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