American Optical Corporation

Robert E Graf

Emil W Deeg

David A Krohn

Robert Joseph Landry

Robert W Young

An ophthalmic glass lens having a compressively-stressed surface zone after ion exchanging which is at least 120 microns in depth, formed from an alkali metal oxide silicate glass comprising by weight about 4 to about 15 percent sodium oxide and about 3 to about 15 percent potassium oxide. There is a compressively-stressed surface layer having a strength of at least 25,000 psi. The total amount of sodium, potassium and other alkali metal oxides is up to about 20 percent. The total amount of zinc oxide, lanthanum oxide, magnesium oxide, and calcium oxide is about 8 to 15 percent, and there is about 3 to about 15 percent phosphorus pentoxide. An ion exchange process takes place at a temperature either above or below the strain point of conventional ophthalmic crown glass to produce satisfactory physical properties in the ophthalmic glass lens.

High strength ophthalmic lens

An ophthalmic glass lens can be prepared by exposing an alkali metal silicate glass to an ion exchange process in which the glass is chemically strengthened by an exchange of potassium ions for sodium ions in the surface layer of the lens at a temperature either above or below the strain point of the glass. The glasses prepared are essentially free of alumina, have adequate strength and substantially increased depth of pentration of the neutral zone even when up to about 6 percent lime is utilized in the preparation of the glass. The effect of lime as a diffusion-retarding agent during the ion exchange process can be overcome (1) by use of an appropriate amount of zinc or magnesium oxide or mixtures thereof so as to maintain an adequate rate of diffusion during ion exchange or (2) by preparation of the glass essentially free of alumina.

A chemically durable, inert optical implant lens and glass composition for the manufacture of same.

Artificial intraocular lens

An ophthalmic glass lens having a compressively stressed surface zone after ion exchanging which is at least 60 micrometers in depth can be formed from an alkali metal oxide silicate glass comprising by weight about 4 to about 15 percent sodium oxide, about 3 to about 15 percent potassium oxide provided the total amount of sodium, potassium and other alkali metal oxides is up to about 20 percent and about 3 to about 15 percent lanthanum oxide. The ion exchange process can take place at a temperature either above or below the strain point of conventional ophthalmic crown glass to produce satisfactory physical properties in the ophthalmic glass lens.

There is disclosed an ion exchange-strengthened ophthalmic segment glass suitable for the fabrication of fused bifocal and trifocal ophthalmic lenses. More particularly, there is disclosed a lanthanum-silicate based ophthalmic segment glass having indices of refraction of about 1.57 to about 1.65 which is suitable for chemical ion exchange strengthening so as to develop a compressively-stressed ion-exchanged surface layer having a depth of at least 60 micrometers.

Ion exchangeable segment glass

Glass having an extremely high absorption coefficient for incident light in fiber optical image transfer devices and working compatibility with conventional light-conducting glasses used in the manufacture of such devices. The glass consists essentially of lanthanum trioxide, boron oxide, manganese dioxide, a colorant and glass forming, modifying and stabilizing ingredients.

Absorptive glass

Laser glasses having high resistance to self-damage during operation are formed in all ceramic melting units, in the presence of a fining agent to eliminate the formation of metallic inclusions and semi-conductive inclusions and using base glass compositions with reduced tendency toward microphase separation and devitrification. The major ingredients of the glass batches include silicon dioxide, alkali and alkaline earth nitrates, carbonates and fluorides. The method involves introducing oxidizing compounds into the reaction mixture in a sufficient amount that during the reaction and fining phase, oxidizing conditions are maintained throughout the entire volume of the glass melt.

Laser glasses with high damage threshold and method of making such

Chemically stable, semiconducting glasses having a resistivity of from about 2 .times. 10.sup.7 to about 6 .times. 10.sup.8 ohm.sup.. cm contain 25 to 35 weight percent of vanadium pentoxide, 10 to 20 weight percent phosphorous pentoxide, and from 35 to 45 weight percent of molybdenum trioxide. These semiconducting glasses are melted readily, are castable into desired shapes, and offer good resistance to devitrification.

Semiconducting glasses and the method of preparation thereof

Faraday rotation glasses exhibiting a high Verdet constant and a low susceptability toward devitrification are formed by introducing a high quantity of rare earth oxides into a borate glass base. The glasses can be melted under standard environmental conditions and may be made on a large scale.

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Southbridge, MA, United States of America

Robert E Graf