| 摘要 |
Optical glass having a refractive index (nd) of 1.75 or greater, and an Abbe number (&ngr;d) 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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