Optical glasses with improved varying partial dispersion in the optical positional range of lanthanum crown glasses and lanthanum flint glasses
AssigneeJenaer Glaswerk Schott & Gen.
InventorsMarga Faulstich, Walter Geffcken
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Abstract
Optical, fluorine containing barium borosilicate glasses having an improved varying partial dispersion in the optical positional range of lanthanum crown and lanthanum flint glasses wherein the ratio of SiO.sub.2 with respect to SiO.sub.2 and B.sub.2 O.sub.3 is at least 0.62 and the content of fluorine in said glass is between 2 and 7 grams per 100 cc of said glass.
Claims12
Optical glasses containing barium borosilicate having a varying partial dispersion P.sub.g,F = (n.sub.g - n.sub.f)/(n.sub.F - n.sub.C) in the optical positional range of lanthanum crown and lanthanum flint glasses having an index of refraction of about 1.642 to 1.742 and v.sub.d of about 44.0 to 58.0 and wherein the amount of SiO.sub.2 present in the glass satisfies the following condition:
- ##EQU2## is at least 0.62 and the content of fluorine in said glass is at least 7 grams per 100 cc. of said glass consisting essentially of:
- ______________________________________ weight percent ______________________________________ SiO.sub.2 20 to 26 B.sub.2 O.sub.3 3 to 8 BaO 20 to 38 MgO 0 to 6 CaO 0 to 18 SrO 0 to 18 La.sub.2 O.sub.3 20 to 32 Y.sub.2 O.sub.3 0 to 25 ThO.sub.2 0 to 18 ______________________________________
- and up to 12 equivalent percent of one or more of the following ingredients to adjust the required n.sub.d and v.sub.d values:
- ZnO, PbO, CdO, TiO.sub.2, ZrO.sub.2, Nb.sub.2 O.sub.5, Ta.sub.2 O.sub.5, WO.sub.3, MO.sub.3 and mixtures thereof.
Dependencies are inferred from the claim text.