| 摘要 |
Disclosed is an optical glass comprising, expressed as weight percentages, greater than or equal to 18 percent and less than 30 percent of SiO2, greater than or equal to 12 percent and less than 23 percent of BaO, 22 to 37 percent TiO2, greater than or equal to 7 percent and less than 16 percent Nb2O5, 5 to 20 percent of Na2O, 0 to 6 percent of K2O, 0 to 5 percent of CaO, 0 to 5 percent of SrO, 0 to 4 percent of ZrO2, 0 to 3 percent of Ta2O5, 0 to 1 percent of Sb2O5, and greater than or equal to 0 percent and less than 0.5 percent of P2O5, and by essentially not comprising PbO, As2O3, and F. The optical glass exhibits a refractive index (nd) greater than or equal to 1.80 and an Abbé number (vd) less than or equal to 30. A method of manufacturing a glass material for press molding is disclosed. This method comprises the steps of melting the glass starting materials, forming the glass melt obtained, and annealing the formed glass and is characterized in that: the glass melt has a composition such that, (1) when rapidly cooled to room temperature, said glass melt becomes glass that has a scattering coefficient of less than 0.005 cm<-1> at wavelengths of from 400 to 2,500 nm or comprises crystals with a volumetric ratio of less than 10<-6>, and (2) when maintained for three hours at a temperature 10 DEG C higher than the glass transition temperature, maintained for 10 min at a temperature yielding a viscosity of 10<4,5> to 10<3,5> dPa • s, and then rapidly cooled to room temperature, said glass melt becomes glass that has a scattering coefficient at at least one wavelength from 400 to 2,500 nm of greater than 0.01 cm<-1> or comprises crystals with a volumetric ratio of greater than 10<-5>; and an annealing of said formed glass is conducted at a temperature lower than the glass transition temperature. <IMAGE> |
