Schott Glass Technologies, Inc.

Karl-Heinz Mader

Reinhard Kassner

Lee M Cook

Roland Schnabel

An ophthalmic glass particularly useful as a segment glass consists essentially of, in weight percent:

Highly prefractive, low dispersion optical glass suitable for multifocal

An optical quality glass suitable for use in ophthalmic lenses having a refractive index of at least 1.59, an Abbe number of at least 40.5, a density of no greater than 2.67 g/cm.sup.-3, and a coefficient of thermal expansion .alpha. of less than 90.times.10.sup.-7 per .degree.C. contains at least 90 mole % of SiO.sub.2, Li.sub.2 O, Na.sub.2 O, K.sub.2 O, CaO, and TiO.sub.2, and essentially does not contain Al.sub.2 O.sub.3, B.sub.2 O.sub.3, or oxides of elements having atomic weights above 90, such as Nb.sub.2 O.sub.5, La.sub.2 O.sub.3, or ZrO.sub.2.

Highly refractive, low dispersion, low density optical glass suitable

Glass surfaces are modified using controlled chemical corrosion to reduce reflection for a variety of existing optical and ophthalmic silicate glass compositions containing at least 5 weight % of alkali metal, using neutral or slightly alkaline aqueous solutions (pH: 7.0-8.5) at temperatures of 20.degree.-100.degree. C. The solutions contain an electrolyte having a dissociation constant greater than 10.sup.-6 and contain a polyvalent metal ion. Selection of the proper range of the ratio of glass surface area treated to treating solution volume is critical for achieving satisfactory results for optical applications as well as for making the process simple, repeatable, and inexpensive. Using this invention, antireflective surfaces may be produced on optical devices of complex configuration with high uniformity. Such surfaces provide substantially improved performance in high energy laser systems where exposure to laser light of extremely high intensity and short duration will destroy or degrade conventionally applied coatings.

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Clarks Summit, PA, United States of America

Karl-Heinz Mader