Optical fluorophosphate glass having anomalous positive partial dispersion and process for its production

US4859635A · kind A · utility

Assignee

• Ernst Leitz Wetzlar, GmbH · DE

Inventors

• Norbert Meinert · Witzenhausen, DE
• Werner Huber · Witzenhausen, DE
• Rainer Dreuth · Wetzlar, DE
• Henning Franek · Solms, DE

Key dates

• Filing date: Nov 8, 1988
• Grant date: Aug 22, 1989
• Expiry date: Nov 8, 2008

Classification

• Technology area (CPC Y): Emerging Cross-Sectional Technologies
• CPC primary: Y10S501/902
• WIPO field: Materials, metallurgy
• WIPO sector: Chemistry

Abstract

Optical fluorophosphate glass which is based on Mg(PO.sub.3).sub.2, Ca(PO.sub.3).sub.2, Ba(PO.sub.3).sub.2, Al(PO.sub.3).sub.3, MgF.sub.2, CaF.sub.2, SrF.sub.2, AlF.sub.3, BaO and SrO and has a refractive index n.sub.e between 1.515 and 1.546, an Abbe value .nu..sub.e between 75.8 and 77.4 and a positive anomalous partial dispersion value .DELTA..nu..sub.e between 14.85 and 15.15. The glass comprises (in weight-%) 2.4-2.7 Mg; 4.5-4.9 Ca; 15.9-17.6 Sr; 20.2-22.3 Ba; 5.6-6.2 Al; 8.8-9.7 P; 22.0-24.3 F and 15.7-17.4 O. The improved physico-chemical parameters, such as linear expansion coefficient, glass transition temperature T.sub.g, density .zeta., Knoop-hardness HK, etc., are stated. Finally, a production process for this optical glass is described.