Process for preparation of fluorophosphate optical glass

摘要

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 .sub.e between 85 and 80 and a positive anomalous partial dispersion value .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.