| 摘要 |
Optical glass having a refractive index (nd) of 1.75 or greater, and an Abbe number (nud) falling within the range of 15 to 40, which is suitable for molding by precision mold press is provided. The optical glass is characterized by including B2O3+SiO2 in an amount of 10 to 70%, Bi2O3 in an amount of 5% or more and less than 25%, RO+Rn2O in an amount of 5 to 60% (wherein R represents one or more selected from a group consisting of Zn, Ba, Sr, Ca, and Mg; and Rn represents one or more selected from a group consisting of Li, Na, K, and Cs), with each component in the range expressed in oxide-based mole, and is characterized in that transparency in the visible region is high, and that the transition point (Tg) is 520° C. or lower. The optical glass is characterized by having a spectral transmittance of 70% or greater at a wavelength of 550 nm, for a thickness of 10 mm.
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