There are provided an optical glass that can compensate for chromatic aberration of glass lenses with high precision because of its high anomalous dispersion, that is lighter than that in the related art, and that is easily handled in a polishing process because of its low degree of abrasion, an optical element, and a preform.

The optical glass contains P.sup.5+, Al.sup.3+, and Zn.sup.2+ as cation components and O.sup.2 and F.sup. as anion components,

wherein the cation components are P.sup.5+ 25% to 40%, Al.sup.3+ 5% to 20%, Zn.sup.2+ 1% to 15%, and Ba.sup.2+ 0% to 28% on a cat. % basis,
the anion components are O.sup.2 40% to 70% and F.sup. 30% to 60% on an ani. % basis, and
the optical glass has a refractive index (nd) of 1.53 to 1.60, an Abbe number (d) of 65 to 75, a partial dispersion ratio g.f of 0.520 to 0.560, and a degree of abrasion of 420 or less.

There are provided an optical glass that can compensate for chromatic aberration of glass lenses with high precision because of its high anomalous dispersion, that is lighter than that in the related art, and that is easily handled in a polishing process because of its low degree of abrasion, an optical element, and a preform.

The optical glass contains P.sup.5+, Al.sup.3+, and Zn.sup.2+ as cation components and O.sup.2 and F.sup. as anion components,

wherein the cation components are P.sup.5+ 25% to 40%, Al.sup.3+ 5% to 20%, Zn.sup.2+ 1% to 15%, and Ba.sup.2+ 0% to 28% on a cat. % basis,
the anion components are O.sup.2 40% to 70% and F.sup. 30% to 60% on an ani. % basis, and
the optical glass has a refractive index (nd) of 1.53 to 1.60, an Abbe number (d) of 65 to 75, a partial dispersion ratio g.f of 0.520 to 0.560, and a degree of abrasion of 420 or less.

Provided is a super low melting SnOSnF2P2O5-based glass frit for which the firing temperature can be set to 200 C. or less and which has high water resistance and transparency. The fluorinated tin-based glass frit includes, in mol %, 30 to 70% of SnF2, 10 to 30% of P2O5, 10 to 40% of SnO, 0.1 to 10% of SnO2, 0 to 5% of In2O3, 0 to 5% of B2O3, and 0 to 5% of SiO2, and has a glass transition point of 160 C. or lower, a softening point of 180 C. or lower, and a maximum particle size of 100 m or less. The fluorinated tin-based glass frit has a visible light transmission rate of 80% or more at 200 C. and a thickness of 0.6 mm of a fired product thereof, and a rate of volume reduction of the fired product due to soaking in hot water at 85 C. for 24 hours is 2 vol. % or less.

Provided is a super low melting SnOSnF2P2O5-based glass frit for which the firing temperature can be set to 200 C. or less and which has high water resistance and transparency. The fluorinated tin-based glass frit includes, in mol %, 30 to 70% of SnF2, 10 to 30% of P2O5, 10 to 40% of SnO, 0.1 to 10% of SnO2, 0 to 5% of In2O3, 0 to 5% of B2O3, and 0 to 5% of SiO2, and has a glass transition point of 160 C. or lower, a softening point of 180 C. or lower, and a maximum particle size of 100 m or less. The fluorinated tin-based glass frit has a visible light transmission rate of 80% or more at 200 C. and a thickness of 0.6 mm of a fired product thereof, and a rate of volume reduction of the fired product due to soaking in hot water at 85 C. for 24 hours is 2 vol. % or less.

Provided are nanophosphor-attached inorganic particles that can suppress the degradation of the nanophosphor when sealed in glass, and a wavelength conversion member using the nanophosphor-attached inorganic particles. The nanophosphor-attached inorganic particle 10 include: inorganic particles 1 having an average particle diameter of 1 m or more; and a nanophosphor 2 attached to surfaces of the inorganic particles 1.

Provided are nanophosphor-attached inorganic particles that can suppress the degradation of the nanophosphor when sealed in glass, and a wavelength conversion member using the nanophosphor-attached inorganic particles. The nanophosphor-attached inorganic particle 10 include: inorganic particles 1 having an average particle diameter of 1 m or more; and a nanophosphor 2 attached to surfaces of the inorganic particles 1.

The disclosed fluorophosphate glasses for an active device include: a metaphosphate composition including Al(PO.sub.3).sub.3; a fluoride composition including BaF.sub.2 and SrF.sub.2; and a dopant composed of ErF.sub.3 and YbF.sub.3, and have thermal and mechanical properties to be able to be used as a glass base material for an active device (e.g., optical fiber laser), have a high emission cross-section characteristic, have a reinforced upconversion and downconversion emission characteristic, and have high sensitivity S in a cryogenic environment.

The disclosed fluorophosphate glasses for an active device include: a metaphosphate composition including Al(PO.sub.3).sub.3; a fluoride composition including BaF.sub.2 and SrF.sub.2; and a dopant composed of ErF.sub.3 and YbF.sub.3, and have thermal and mechanical properties to be able to be used as a glass base material for an active device (e.g., optical fiber laser), have a high emission cross-section characteristic, have a reinforced upconversion and downconversion emission characteristic, and have high sensitivity S in a cryogenic environment.

Disclosed is fluorophosphate glasses for an active device, the fluorophosphate glasses including: a metaphosphate composition including Mg(PO.sub.3).sub.2 of about 20 mol % to about 60 mol %; a fluoride composition including BaF.sub.2 of about 20 mol % to about 60 mol % and CaF.sub.2 of about 0 mol % to about 40 mol %; and dopants including rare earth elements, in which there is an effect of increasing a carrier lifetime at a metastable state energy level that is stimulated-emitted due to an efficient energy transfer phenomenon by composition optimization of dopants (e.g. Er and Yb).

Disclosed is fluorophosphate glasses for an active device, the fluorophosphate glasses including: a metaphosphate composition including Mg(PO.sub.3).sub.2 of about 20 mol % to about 60 mol %; a fluoride composition including BaF.sub.2 of about 20 mol % to about 60 mol % and CaF.sub.2 of about 0 mol % to about 40 mol %; and dopants including rare earth elements, in which there is an effect of increasing a carrier lifetime at a metastable state energy level that is stimulated-emitted due to an efficient energy transfer phenomenon by composition optimization of dopants (e.g. Er and Yb).