Optical glass composition, preform and optical element

An optical glass composition comprising, in % by weight,

• 1.0% or more and 12.0% or less of SiO2,
• 8.0% or more and 18.0% or less of B2O3,
• 0% or more and 6.0% or less of ZnO,
• 1.0% or more and 10.0% or less of ZrO2,
• 25.0% or more and 47.0% or less of La2O3,
• 0% or more and 5.0% or less of R2O (here, R is at least one of Li, Na and K),
• 0% or more and 15.0% or less of BaO,
• 0% or more and 15.0% or less of Nb2O5,
• 0% or more and 7.0% or less of TiO2,
• 0% or more and 15.0% or less of Ta2O5,
• 2.0% or more of Nb2O5+TiO2+Ta2O5,
• 0% or more and 20.0% or less of Gd2O3,
• 0.5% or more and 10.0% or less of WO3 and
• 10.0% or more and 16.0% or less of Nb2O5+WO3, and having
• a refractive index (nd) to the d-line of 1.88 or higher and 1.92 or lower and an Abbe number (νd) to the d-line of 33 or higher and 37 or lower.

An optical glass composition comprising, in % by weight,

• 1.0% or more and 12.0% or less of SiO2,
• 8.0% or more and 18.0% or less of B2O3,
• 0% or more and 6.0% or less of ZnO,
• 1.0% or more and 10.0% or less of ZrO2,
• 25.0% or more and 47.0% or less of La2O3,
• 0.5% or more and 4.0% or less of Li2O,
• 0% or more and 16.0% or less of Nb2O5,
• 0% or more and 7.0% or less of TiO2,
• 0% or more and 15.0% or less of Ta2O5,
• 1.0% or more of Nb2O5+TiO2+Ta2O5,
• 0% or more and 26.0% or less of Gd2O3 and
• 0% or more and 15.0% or less of WO3, and having
• a refractive index (nd) to the d-line of 1.88 or higher and 1.92 or lower, an Abbe number (νd) to the d-line of 33 or higher and 37 or lower and a yield temperature of 700° C. or lower.

An optical glass composition comprising, in % by weight,

• 1.0% or more and 12.0% or less of SiO2,
• 8.5% or more and 18.0% or less of B2O3,
• 0% or more and 6.0% or less of ZnO,
• 1.0% or more and 10.0% or less of ZrO2,
• 25.0% or more and 47.0% or less of La2O3,
• 0% or more and 5.0% or less of R2O (here, R is at least one of Li, Na and K),
• 0% or more and 16.0% or less of Nb2O5,
• 0% or more and 7.0% or less of TiO2,
• 0% or more and 15.0% or less of Ta2O5,
• 1.0% or more of Nb2O5+TiO2+Ta2O5,
• 0% or more and 26.0% or less of Gd2O3 and
• 0% or more and 13.0% or less of WO3, and
• substantially not containing R′O (here, R′ is at least one of Ba, Sr, Ca and Mg), and having
• a refractive index (nd) to the d-line of 1.88 or higher and 1.92 or lower and an Abbe number (νd) to the d-line of 33 or higher and 37 or lower.