A glass includes a composition characterized by the following constituent phases (in mol-%): 20-80 lanthanum titanate; 10-50 lanthanum niobate; 0-60 lanthanum molybdenum borate; 2-40 lanthanum borate; 2-40 yttrium borate; 0-40 gadolinium borate; 2-40 zirconium silicate; 2-40 diboron trioxide; and 0-20 silicon dioxide. A refractive index is at least 2.00.

Provided is an optical glass plate having a high refractive index and excellent visible light transmittance. An optical glass plate characterized by containing as a glass composition at least one selected from Nb.sub.2O.sub.5, La.sub.2O.sub.3, and Gd.sub.2O.sub.3, the optical glass plate having a refractive index (nd) of 1.90 to 2.30 and an internal transmittance τ.sub.450 of 75% or greater for a thickness of 10 mm at a wavelength of 450 nm.

A glass (excluding glass used for optical elements selected from the group consisting of lenses and prisms and glass used for optical fibers) has an oxide-basis glass composition based on a mass basis of a SiO.sub.2 content of 0 to 25%, a B.sub.2O.sub.3 content of 0 to 35%, a P.sub.2O.sub.5 content of 0 to 30%, a total content of SiO.sub.2, B.sub.2O.sub.3, and P.sub.2O.sub.5 (SiO.sub.2+B.sub.2O.sub.3+P.sub.2O.sub.5) of 10 to 45%, an Al.sub.2O.sub.3 content of 0 to 15%, a Li.sub.2O content of 0 to 2%, a Na.sub.2O content of 0 to 10%, a K.sub.2O content of 0 to 10%, a Rb.sub.2O content of 0 to 5%, a Cs.sub.2O content of 0 to 5%, a total content of Li.sub.2O, Na.sub.2O, K.sub.2O, Rb.sub.2O, and Cs.sub.2O (Li.sub.2O+Na.sub.2O+K.sub.2O+Rb.sub.2O+Cs.sub.2O) of 0 to 15%, and has a wetting angle to water of 60° or more.

A glass (excluding glass used for optical elements selected from the group consisting of lenses and prisms and glass used for optical fibers) has an oxide-basis glass composition based on a mass basis of a SiO.sub.2 content of 0 to 25%, a B.sub.2O.sub.3 content of 0 to 35%, a P.sub.2O.sub.5 content of 0 to 30%, a total content of SiO.sub.2, B.sub.2O.sub.3, and P.sub.2O.sub.5 (SiO.sub.2+B.sub.2O.sub.3+P.sub.2O.sub.5) of 10 to 45%, an Al.sub.2O.sub.3 content of 0 to 15%, a Li.sub.2O content of 0 to 2%, a Na.sub.2O content of 0 to 10%, a K.sub.2O content of 0 to 10%, a Rb.sub.2O content of 0 to 5%, a Cs.sub.2O content of 0 to 5%, a total content of Li.sub.2O, Na.sub.2O, K.sub.2O, Rb.sub.2O, and Cs.sub.2O (Li.sub.2O+Na.sub.2O+K.sub.2O+Rb.sub.2O+Cs.sub.2O) of 0 to 15%, and has a wetting angle to water of 60° or more.

A glass powder composite includes a first glass powder, and a second glass powder having a different solubility from that of the first glass powder depending on pH, wherein both the first glass powder and the second glass powder have ion sustained-release properties.

Provided is a magneto-optic element that enables easy size reduction of an optical isolator. A magneto-optic element is formed of two or more magnetic members joined together.

Provided is a magneto-optic element that enables easy size reduction of an optical isolator. A magneto-optic element is formed of two or more magnetic members joined together.

An optical glass has a refractive index n.sub.d of more than 2.10 and includes at least TiO.sub.2, NbO.sub.2.5, LaO.sub.1.5, SiO.sub.2, and B.sub.2O.sub.3. The glass has the following features: a cation parameter K of 1.8<K≤2.8, wherein K=(Ti-eq.+SiO.sub.2+(BO.sub.1.5)/2)/(La-eq.), the molar fractions of Ti-eq., SiO.sub.2, BO.sub.1.5 and La-eq. in the cation parameter K being in cat %; a sum total of glass components SiO.sub.2 and B.sub.2O.sub.3 of 8.0 mol %≤(SiO.sub.2+B.sub.2O.sub.3)≤20.0 mol %, the proportion of B.sub.2O.sub.3 being >0 mol % and the proportion of SiO.sub.2>0 mol %; and a temperature T.sub.max≤1330° C.

An optical glass has a refractive index n.sub.d of more than 2.10 and includes at least TiO.sub.2, NbO.sub.2.5, LaO.sub.1.5, SiO.sub.2, and B.sub.2O.sub.3. The glass has the following features: a cation parameter K of 1.8<K≤2.8, wherein K=(Ti-eq.+SiO.sub.2+(BO.sub.1.5)/2)/(La-eq.), the molar fractions of Ti-eq., SiO.sub.2, BO.sub.1.5 and La-eq. in the cation parameter K being in cat %; a sum total of glass components SiO.sub.2 and B.sub.2O.sub.3 of 8.0 mol %≤(SiO.sub.2+B.sub.2O.sub.3)≤20.0 mol %, the proportion of B.sub.2O.sub.3 being >0 mol % and the proportion of SiO.sub.2>0 mol %; and a temperature T.sub.max≤1330° C.

A glass article has a refractive index n.sub.G≥1.95 and an R-number in a range of from 0.900 to 1.050. The R-number is calculated according to the following formula:

[00001]$R=\left(n_G-1\right)\left(\frac{\ln \left[\frac{{\lambda }_G^2-{\lambda }_{\min }^2}{{\lambda }_G^2-{\lambda }_{\max }^2}.Math.\frac{{\lambda }_{\max }^2}{{\lambda }_{\min }^2}\right]}{42\ln \left[\frac{{\lambda }_B^2-{\lambda }_{\min }^2}{{\lambda }_B^2-{\lambda }_{\max }^2}.Math.\frac{{\lambda }_R^2-{\lambda }_{\max }^2}{{\lambda }_R^2-{\lambda }_{\min }^2}\right]}+\frac{1}{2.8}\right).$

λ.sub.R=656 nm, λ.sub.G=587 nm and λ.sub.B=486 nm, λ.sub.min=33 nm, and n.sub.G is a refractive index of the glass article at a wavelength of 587 nm.