Optical glass and optical product using the same

A method of manufacturing glass products comprising heating a press-moldable glass perform;

• and precisely press molding the heated glass perform to obtain a glass product, wherein said glass perform is prepared by the method wherein a prescribed amount of a piece of molten optical glass flowing out of a flowout pipe is received in a receiving mold to prepare a glass perform, wherein the optical glass exhibits a refractive index in the range of from 1.75 to 2.0, an Abbé number in the range of from 20 to 28.5, and a viscosity at the liquid phase temperature equal to or higher than 0.4 Pa·s, wherein said optical glass comprises, as molar percentages:
• 12-34 percent of P2O5;
• 0.2-15 percent of B2O3, where the total quantity of P2O 5 and B2O3 is 15-35 percent;
• 2-40 percent of WO3;
• 0-25 percent (excluding 0 percent) of Nb2O5;
• 0 to 10 percent (excluding 0 percent) of TiO2, where the total quantity of WO3, Nb2O5 and TiO2 is 20-45 percent;
• 0-25 percent (excluding 0 percent) of BaO;
• 0-20 percent (excluding 0 percent) of ZnO, where the total quantity of BaO and ZnO is less than 30 percent;
• 2-30 percent of Li2O;
• 2-30 percent of Na2O;
• 0-15 percent (excluding 0 percent) of K2O, where the total quantity of Li2O, Na2O, and K2O is 29-45 percent;
• 0-10 percent of CaO;
• 0-10 percent of SrO;
• 0-5 percent of Al2O3;
• 0-5 percent of Y2O3;
• 0-1 percent of Sb2O3;
• and
• 0-1 percent of As2O3, where the total quantity of all of the above-listed components is equal to or more than 94 percent;
• and
• wherein said optical glass comprises, as essential components, P2O5, B2O3, WO3, Nb2O5, TiO2, BaO, ZnO, Li2O, Na2O and K2O, and does not comprise an amount of GeO2.