Optical CdO and ThO.sub.2 -free glass with refractive indices of 1.73-1.78 abbe numbers of 30-34, and high devitrification stability

US4824809A · kind A · utility

Assignee

• Schott Glaswerke · DE

Inventors

• Danuta Grabowski · Wiesbaden, DE
• Ludwig Ross · Klein-Winternheim, DE

Key dates

• Filing date: Dec 28, 1987
• Grant date: Apr 25, 1989
• Expiry date: Dec 28, 2007

Classification

• Technology area (CPC C): Chemistry; Metallurgy
• CPC primary: C03C3/072
• WIPO field: Materials, metallurgy
• WIPO sector: Chemistry

Abstract

A new, CdO-and ThO.sub.2 -free optical glass with refractive indices of 1.73-1.78 and Abbe numbers of 30-34 and with particularly good devitrification stability comprises (in weight %): ______________________________________ SiO.sub.2 12-20, B.sub.2 O.sub.3 10-18, PbO 50-60 Al.sub.2 O.sub.3 2-7, ZnO 0-4, ZrO.sub.2 0.5-3 La.sub.2 O.sub.3 2-10, Cs.sub.2 O 0-5, M.sub.2 O 0-1 (M.sub.2 O.dbd. Na.sub.2 O, K.sub.2 O, Li.sub.2 O) TiO.sub.2 0-5 with the SiO.sub.2 /B.sub.2 O.sub.3 -ratio being about 1.0 to ______________________________________ 1.5.