The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
May. 04, 1976
Filed:
Oct. 15, 1974
Georg Gliemeroth, Mainz, DT;
Lothar Meckel, Oestrich, DT;
Jenaer Glaswerk Schott & Gen., Mainz, DT;
Abstract
A chemically hardened optical crown glass having a refractive index n.sub.d of 1.5225-1,5235, a thermal expansion coefficient in the temperature range between 20.degree. and 300.degree. C. of 90 .times. 10.sup.-.sup.7 to 100 .times. 10.sup.-.sup.7 /.degree.C., a dispersion .gamma.d of 54-60, a softening temperature of 690.degree.-750.degree. C., and a transformation temperature of 480.degree.-550.degree. C., produced by melting, shaping and cooling a batch consisting essentially of the following composition in parts by weight based on 100 parts of total composition: SiO.sub.2, 50.5-61.0; Al.sub.2 O.sub.3, 7.0-17.5; B.sub.2 O.sub.3, 2.0-6.1; Li.sub.2 O, 0-1.0; Na.sub.2 O, 12.0-15.0; K.sub.2 O, 2.5-3.5; CaO, 0-4.1; BaO, 0-0.3; ZnO, 5.0-10.0; PbO, 0-0.5; TiO.sub.2, 0.1-0.9; As.sub.2 O.sub.3, 0-0.5; and Sb.sub.2 O.sub.3, 0-1.0; and thereafter subjected to an ion exchange in which large alkali metal ions are diffused into the glass in exchange for smaller alkali metal ions at a temperature below the upper cooling temperature which corresponds to a viscosity of 10.sup.13 poises.