Optical glass of negative anomalous partial dispersion in the blue region

US5137850A · kind A · utility

Assignee

• Schott Glaswerke · DE

Inventors

• Marc Clement · Mainz, DE
• Volkmar Geiler · Ingelheim am Rhein, DE
• Danuta Grabowski · Wiesbaden, DE

Key dates

• Filing date: Jan 16, 1991
• Grant date: Aug 11, 1992
• Expiry date: Jan 16, 2011

Classification

• Technology area (CPC Y): Emerging Cross-Sectional Technologies
• CPC primary: Y10S501/903
• WIPO field: Materials, metallurgy
• WIPO sector: Chemistry

Abstract

A chemically resistant glass which can be produced at relatively low melting temperatures and has anomalous negative partial dispersion P.sub.g,F, a refractive index n.sub.d of from 1.73 to 1.83 and an Abbe coefficient v.sub.d of from 31 to 38 preferably contains (in % by weight, based on oxides): ______________________________________ 0-4 SiO.sub.2 + GeO.sub.2 0-2 GeO.sub.2 0-10 MgO 26-33 B.sub.2 O.sub.3 0-1 Li.sub.2 O 0-16 CaO 19-50 PbO 0-1 Na.sub.2 O 0-16 BaO 1-6 ZrO.sub.2 0-1 K.sub.2 O 0-16 SrO 4-16 Ta.sub.2 O.sub.5 0-2 .SIGMA. alkaline earth 0-6 Al.sub.2 O.sub.3 metal oxides 0-16 ZnO 0-4 TiO.sub.2 1.5-20 .SIGMA. alkaline earth metal oxides + ZnO 0-1 WO.sub.3 0-11 La.sub.2 O.sub.3 0-7 Nb.sub.2 O.sub.5 0-5.5 Y.sub.2 O.sub.3 0-5.5 Gd.sub.2 O.sub.3 4-11 .SIGMA. La.sub.2 O.sub.3 + Y.sub.2 O.sub.3 + Gd.sub.2 O.sub.3 ______________________________________ with the proviso that the .SIGMA.(SiO.sub.2 +GeO.sub.2 +B.sub.2 O.sub.3)/.SIGMA.(ta.sub.2 O.sub.5 +ZrO.sub.2 +HfO.sub.2) ratio is less than 5 and the PbO/.SIGMA.(SiO.sub.2 +GeO.sub.2 +B.sub.2 O.sub.3) ratio is less than 1.7, and, if desired, conventional refining assistants.