Process for preparation of fluorophosphate optical glass

US4915721A · kind A · utility

Assignee

• Ernst Leitz Wetzlar, GmbH · DE

Inventors

• Heinz Broemer · Wetzlar, DE
• Werner Huber · Witzenhausen, DE
• Norbert Meinert · Witzenhausen, DE

Key dates

• Filing date: Jul 5, 1989
• Grant date: Apr 10, 1990
• Expiry date: Jul 5, 2009

Classification

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

Abstract

Optical fluorophosphate glasses based on Ba(PO.sub.3).sub.2, Al(PO.sub.3).sub.3, alkaline earth metal fluorides and AlF.sub.3 are described which have a refractive index n.sub.e between 1.47 and 1.50, an Abbe-value .nu..sub.e between 85 and 80 and a positive anomalous partial dispersion value .DELTA..nu..sub.e between +17 and +22. They comprise (in wt.-%) 0.5-3 Mg, 8-10 Ca, 12-20 Sr, 9-12 Ba, 7-9 Al, 5-9 P, 8-12 O and 35-38 F. Ti, Na, K and H may additionally be present. The improved physico-chemical parameters (expansion coefficient, glass transition temperature, density, Knoop-hardness) and the transmission characteristics are given, and a process for producing these optical glasses is described.