Optical glass, press-molding glass gob and optical element
AssigneeHoya Corporation
InventorMichio Endo
Life of this patent
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Abstract
An optical glass having a remarkably high refractive index and excellent stability can be give without being based on PbO, and the optical glass contains, as essential components, at least one oxide selected from La2O3, Gd2O3, Y2O3, Yb2O3, TiO2, Nb2O5 or WO3, at least one oxide selected from MgO, CaO, SrO or BaO and B2O3 and optionally containing SiO2, wherein on the basis of mass, the total content of B2O3 and SiO2 is from 1 to 25%, the ratio of (B2O3+SiO2)/(La2O3+Gd2O3+Y2O3+Yb2O3+TiO2+Nb2O5+WO3) is from 0.05 to 0.3 and the ratio of (MgO+CaO+SrO+BaO)/(La2O3+Gd2O3+Y2O3+Yb2O3+TiO2+Nb2O5+WO3) is from 0.1 to 0.4, the optical glass having a refractive index (nd) of 2.000 or more and an Abbe's number (vd) of 27 or less.
Claims13
An optical glass comprising, as essential components, at least one oxide selected from La2O3, Gd2O3, Y2O3, Yb2O3, TiO2, Nb2O5 and WO3, at least one oxide selected from MgO, CaO, SrO and BaO, and B2O3 and optionally containing SiO2, wherein on the basis of mass,
- (a) the total content of B2O3 and SiO2 is from 1 to 25%,
- (b) the ratio of the total content of B2O3 and SiO2 to the total content of La2O3, Gd2O3, Y2O3, Yb2O3, TiO2, Nb2O5 and WO3, (B2O3+SiO2)/(La2O3+Gd2O3+Y2O3+Yb2O3+TiO2+Nb2O5+WO3), is from 0.05 to 0.3, and
- (c) the ratio of the total content of MgO, CaO, SrO and BaO to the total content of La2O3, Gd2O3, Y2O3, Yb2O3, TiO2, Nb2O5 and WO3, (MgO+CaO+SrO+BaO)/(La2O3+Gd2O3+Y2O3+Yb2O3+TiO2+Nb2O5+WO3), is from 0.1 to 0.4,
- the optical glass having a refractive index (nd) of 2.000 or more, an Abbe's number (vd) of 27 or less and is substantially free of PbO.
Dependencies are inferred from the claim text.