Glasses containing silicon dioxide (SiO.sub.2) and/or boron oxide (B.sub.2O.sub.3) as glass formers and having a refractive index n.sub.d of greater than or equal to 1.80, as measured at 587.56 nm, a density of less than or equal to 5.5 g/cm.sup.3, as measured at 25? C., and a high transmittance to, particularly to blue light, are provided. Optionally, the glasses may be characterized by a high transmittance in the visible and near-ultraviolet (near-UV) range of the electromagnetic spectrum and/or good glass forming ability.

Glasses containing silicon dioxide (SiO.sub.2) and/or boron oxide (B.sub.2O.sub.3) as glass formers and having a refractive index n.sub.d of greater than or equal to 1.80, as measured at 587.56 nm, a density of less than or equal to 5.5 g/cm.sup.3, as measured at 25? C., and a high transmittance to, particularly to blue light, are provided. Optionally, the glasses may be characterized by a high transmittance in the visible and near-ultraviolet (near-UV) range of the electromagnetic spectrum and/or good glass forming ability.

An optical glass with high refractive index and low dispersion, having refractive index nd of 1.78-1.95, Abbe number d of 32-50, and contains no GeO.sub.2, so it is not easily devitrified. An optical glass, represented by cation %, including: 1-20% of Si.sup.4+; 25-60% of B.sup.3+; 10-40% of La.sup.3+; 0-15% of Y.sup.3+; 0-20% of Nb.sup.5+; 0-15% of Ti.sup.4+; 0-10% of Ta.sup.5+; 0-5% of W.sup.6+; 0-15% of Zr.sup.4+; 0-10% of Zn.sup.2+; 0-10% of Bi.sup.3+. An optical glass with excellent transmittance, an optical glass preform and an optical element formed by the above optical glass. The optical element made by the above optical glass and the above glass preform or optical element blank, such as lens, can be used for optical systems.

An optical glass with high refractive index and low dispersion, having refractive index nd of 1.78-1.95, Abbe number vd of 32-50, and contains no GeO.sub.2, so it is not easily devitrified. An optical glass, represented by cation %, including: 1-20% of Si.sup.4+; 25-60% of B.sup.3+; 10-40% of La.sup.3+; 0-15% of Y.sup.3+; 0-20% of Nb.sup.5+; 0-15% of Ti.sup.4+; 0-10% of Ta.sup.5+; 0-5% of W.sup.6+; 0-15% of Zr.sup.4+; 0-10% of Zn.sup.2+; 0-10% of Bi.sup.3+. An optical glass with excellent transmittance, an optical glass preform and an optical element formed by the above optical glass. The optical element made by the above optical glass and the above glass preform or optical element blank, such as lens, can be used for optical systems.

Glasses containing silicon dioxide (SiO.sub.2) and/or boron oxide (B.sub.2O.sub.3) as glass formers and having a refractive index n.sub.d of greater than or equal to 1.80, as measured at 587.56 nm, a density of less than or equal to 5.5 g/cm.sup.3, as measured at 25 C., and a high transmittance to, particularly to blue light, are provided. Optionally, the glasses may be characterized by a high transmittance in the visible and near-ultraviolet (near-UV) range of the electromagnetic spectrum and/or good glass forming ability.

Glasses containing silicon dioxide (SiO.sub.2) and/or boron oxide (B.sub.2O.sub.3) as glass formers and having a refractive index n.sub.d of greater than or equal to 1.80, as measured at 587.56 nm, a density of less than or equal to 5.5 g/cm.sup.3, as measured at 25 C., and a high transmittance to, particularly to blue light, are provided. Optionally, the glasses may be characterized by a high transmittance in the visible and near-ultraviolet (near-UV) range of the electromagnetic spectrum and/or good glass forming ability.

A optical glass comprising: by mol % of a cation, 5% to 35% of a content rate of La.sup.3+; 5% to 25% of a content rate of Si.sup.4+; 5% to 35% of a content rate of Nb.sup.5+; 0% to 20% of a content rate of Ti.sup.4+; and 45% to 80% of a total content rate of Ti.sup.4+, Zr.sup.4+, Nb.sup.5+, Ta.sup.5+, and Al.sup.3+ (Ti.sup.4++Zr.sup.4++Nb.sup.5++Ta.sup.5++Al.sup.3+).

An optical glass includes, in terms of mol % of cations, a total amount of La.sup.3+, Y.sup.3+, and Gd.sup.3+ components falling within a range of from 5% to 65% and a total amount of Zr.sup.4+, Hf.sup.4+, and Ta.sup.5+ components falling within a range of from 5% to 65%, and a relationship expressed in Expression (1) given below is satisfied. (La.sup.3++Y.sup.3++Gd.sup.3+)(Zr.sup.4++Hf.sup.4++Ta.sup.5+)400(%).sup.2.

An optical glass having the following oxides in mass percentage relative to a total mass of the optical glass: 10.0%-30.0% SiO.sub.2, 10.0%-30.0% P.sub.2O.sub.5, 0.1%-5.0% B.sub.2O.sub.3, 0.1%-10.0% Al.sub.2O.sub.3, 0.1%-10.0% Rn oxides, 1.0%-20.0% R oxides, 0.1%-5.0% ZrO.sub.2, 10.0%-30.0% TiO.sub.2, 15.0%-50.0% Nb.sub.2O.sub.5, 0.1%-10.0% Ln oxides, and 0.1%-10.0% WO.sub.3, wherein TiO.sub.2+Nb.sub.2O.sub.5+P.sub.2O.sub.5+the R oxides accounts for 60.01% or above.