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US 5,858,898 AGranted
Optical glass having a negative anomalous dispersion
AssigneeKabushiki Kaisha Ohara
InventorsMuneo Nakahara, Michiko Morishita
Life of this patent
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Abstract
An optical glass having optical constants of refractive index within the range of 1.55-1.75 and Abbe number (.nu. d) within the range of 25-51 and having large negative anomalous dispersion which is substantially free of lead and arsenic compounds includes as its essential ingredients in weigth percent 10->40% SiO.sub.2, 12.5-35% B.sub.2 O.sub.3, 3-20% ZrO.sub.2 and 6-30% Nb.sub.2 O.sub.5.
Claims2
An optical glass consisting in weight percent of:
- ______________________________________ SiO.sub.2 10->40% B.sub.2 O.sub.3 12.5-35% ZrO.sub.2 3-20% Nb.sub.2 O.sub.5 6-30% Li.sub.2 O 0-5% Na.sub.2 O 0-25% K.sub.2 O 0-10% MgO + CaO >5% in which MgO 0->5% CaO 0->5% SrO 0-15% BaO 0-20% ZnO 0-15% Al.sub.2 O.sub.3 0-3% La.sub.2 O.sub.3 0-10% Ta.sub.2 O.sub.5 0-15% P.sub.2 O.sub.5 0->5% GeO.sub.2 0-5% SnO.sub.2 0-2% WO.sub.3 0-5% Sb.sub.2 O.sub.3 0-1% and a fluoride or fluorides of a 0-5% metal element or elements contained in the above metal oxides, a total amount of F contained in the fluoride or fluorides. ______________________________________
Dependencies are inferred from the claim text.