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US 5,332,700 AGranted
High dispersion optical glass
AssigneeKabushiki Kaisha Ohara
InventorsKatsuhiko Yamaguchi, Futoshi Ishizaki, Naoyuki Goto, Hisao Yatsuda, Goro Enomoto, Hideo Yasui
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Abstract
An optical glass which is a SiO.sub.2 -Nb.sub.2 O.sub.5 -R'.sub.2 O (where R' is an alkali metal element)-F system of a specific composition range exhibits optical constants of a refractive index (Nd) of about 1.52-1.67 and an Abbe number (.upsilon. d) of about 32-50, is free of PbO and has an improved light transmissivity.
Claims8
A high dispersion optical glass which comprises in weight percent:
- ______________________________________ SiO.sub.2 47-70% Al.sub.2 O.sub.3 0-15% Nb.sub.2 O.sub.5 15.5-35% TiO.sub.2 0-15% ZrO.sub.2 0-10% LiO.sub.2 + Na.sub.2 O + K.sub.2 O 10-35% in which LiO.sub.2 0-10% Na.sub.2 O 0-20% K.sub.2 O 0-20% ZnO + MgO + CaO + SrO + BaO 0-2% and a fluoride or fluorides of 0.1-10%. a metal element or elements contained in one or more of the above metal oxide or oxides, said fluoride or fluorides substituting for said metal oxides partially or entirely, and a total amount of F contained in the fluoride or fluorides ______________________________________ essentially of in weight percent:
A high dispersion optical glass which consists
- ______________________________________ SiO.sub.2 47-70% Al.sub.2 O.sub.3 0-15% Nb.sub.2 O.sub.5 15.5-35% TiO.sub.2 0-15% ZrO.sub.2 0-10% LiO.sub.2 + Na.sub.2 O + K.sub.2 O 10-35% in which LiO.sub.2 0-10% Na.sub.2 O 0-20% K.sub.2 O 0-20% ZnO + MgO + CaO + SrO + BaO 0-2% and a fluoride or fluorides of a metal element or 0.1-10%. elements contained in one or more of the above metal oxide or oxides, said fluoride or fluorides substituting for said metal oxides partially or entirely, and a total amount of F contained in the fluoride or fluorides ______________________________________
Dependencies are inferred from the claim text.