PRECISION PRESS MOLDING OPTICAL GLASS, PRECISION PRESS MOLDING PREFORM AND METHOD OF MANUFACTURING THE SAME, OPTICAL ELEMENT AND METHOD OF MANUFACTURING THE SAME

摘要

PROBLEM TO BE SOLVED: To provide optical glass for an optical element having a low dispersion characteristic and good resistance to cleaning, the optical element, a method for manufacturing the optical element, a glass preform for producing the optical element, and a method for manufacturing the glass preform.;SOLUTION: The optical glass comprises ≥5 mol% of P₂O₅, has an Abbe number (νd) of ≥58 and a glass transition temperature (Tg) of ≤570°C, and has an alkalinity resistance defined as a rate of mass reduction of ≤17 μg/(cm²×h) when the surface of the optical glass which has been optically polished is immersed in 0.01 mol/L of NaOH aqueous solution at 50°C. A method for manufacturing a precision press molding preform comprised of the optical glass is provided, wherein molten glass of the required mass is separated from a molten glass flow flowing out from an outflow pipe, or molten glass is caused to flow out and molded to obtain a glass molded article, and the glass molded article is mechanically processed. The optical element is comprised of the optical glass. The method for manufacturing the optical element comprises heating a preform and precision press molding the heated preform with a pressing mold, wherein the preform is the above preform or a preform manufactured by the above method.;COPYRIGHT: (C)2011,JPO&INPIT