Optical glass with refractive indices>1.90, Abbe numbers>25 and high chemical stability
AssigneeSchott Glaswerke
InventorsDanuta Grabowski, Ludwig Ross, Volkmar Geiler, Karl Mennemann, Georg Gliemeroth
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Abstract
Optical glass with refractive indicies.gtoreq.1.90, Abbe numbers.gtoreq.25 consisting essentially of, in weight percent; 0-10 SiO.sub.2, 2-20 B.sub.2 O.sub.3, 0-2 Al.sub.2 O.sub.3, the sum of SiO.sub.2, B.sub.2 O.sub.3, and Al.sub.2 O.sub.3 being 7.5-25, 1-16 TiO.sub.2, 0-10 ZrO.sub.2, 35-55 La.sub.2 O.sub.3, 0.5-10 Y.sub.2 O.sub.5, 0.5-15 Nb.sub.2 O.sub.5, 0-10 Gd.sub.2 O.sub.3, 0-15 Ta.sub.2 O.sub.5, 0-3 P.sub.2 O.sub.5 wherein the ratio of SiO.sub.2 to B.sub.2 O.sub.3 is between 0.1 and 1.6, and the sum of Nb.sub.2 O.sub.5 and Ta.sub.2 O.sub.5 is from 9 to 20%.
Claims19
Optical glass with refractive indices .gtoreq. 1.90, Abbe numbers .gtoreq.25 and particularly good chemical stability (erosion times for 1 um from a polished surface by 0.5 n HNO.sub.3 more than 50 hours) as well as high crystallization stability in the viscosity range <100 dPas, consisting essentially of, in percent by weight:
- ______________________________________ SiO.sub.2 0-10 B.sub.2 O.sub.3 2-20 Al.sub.2 O.sub.3 0-2 .SIGMA. SiO.sub.2, B.sub.2 O.sub.3, Al.sub.2 O.sub.3 7.5-25 TiO.sub.2 1-16 ZrO.sub.2 0-10 La.sub.2 O.sub.3 35-55 Y.sub.2 O.sub.3 0.5-10 Nb.sub.2 O.sub.5 0.5-15 Gd.sub.2 O.sub.3 0-10 Ta.sub.2 O.sub.5 0-15 P.sub.2 O.sub.5 0-3 ______________________________________
- wherein the ratio of SiO.sub.2 to B.sub.2 O.sub.3 is between 0.1 and 1.6, and the sum of Nb.sub.2 O.sub.5 Ta.sub.2 O.sub.5 is from 9 to 20% by weight.
Dependencies are inferred from the claim text.