Optical glass; press-molding preform and method of manufacturing same; and optical element and method of manufacturing same

摘要

The present invention relates to optical glass having a high refractive index, high dispersion, and a low glass transition temperature; a preform comprised of the optical glass for precision press-molding and a method of manufacturing the same; and an optical element comprised of the optical glass and a method of manufacturing the same. An example of the optical glasses for precision press molding is characterized by comprising essential components in the form of P₂O₅, Nb₂O₅, WO₃, TiO₂, Bi₂O₃, Li₂O, and Na₂O; comprising optional components in the form of B₂O₃, BaO, ZnO, K₂O, Sb₂O₃, and As₂O₃; where the content of Bi₂O₃ exceeds 4 weight percent but does not exceed 15 molar percent; the content of Li₂O exceeds 3 weight percent but does not exceed 15 weight percent; the combined quantity of Nb₂O₅, WO₃, TiO₂, and Bi₂O₃ is from 25 to 45 molar percent; the combined quantity of Li₂O, Na₂O, and K₂O is less than or equal to 42 molar percent; the combined quantity of the essential components and optional components is greater than or equal to 98 molar percent; the refractive index (nd) is from 1.75 to 2.0; and the Abbé number (nud) is from 18 to 30.