Patent Number: 7,087,543

Title: Optical glass, press-molding preform and optical element

Abstract: An optical glass having a refractive index (nd) of 1.57 to 1.67, an Abbe's number (.nu.d) of 55 to 65 and a glass transition temperature (Tg) of 560.degree. C. or lower and having a low-temperature softening property and excellent climate resistance or a haze value of 3% or less, or an optical glass comprising, by mol %, 22 to 40% of B.sub.2O.sub.3, 12 to 40% of SiO.sub.2, 2 to 20% of Li.sub.2O, 5 to 15% of CaO, 2 to 14% of ZnO, 0.5 to 4% of La.sub.2O.sub.3, 0 to 3% of Gd.sub.2O.sub.3, 0 to 3% of Y.sub.2O.sub.3, the total content of La.sub.2O.sub.3, Gd.sub.2O.sub.3 and Y.sub.2O.sub.3 being at least 1%, 0 to 5% of Al.sub.2O.sub.3, 0 to 3% of ZrO.sub.2 and 0 to 5% of BaO, the total content of the above components being more than 96%, and having a refractive index (nd) of 1.57 to 1.67 and an Abbe's number (.nu.d) of 55 to 65.

Inventors: Kasuga; Yoshiko (Tokyo, JP), Zou; Xuelu (Tokyo, JP)

Assignee: Hoya Corporation

International Classification: C03C 3/066 (20060101); C03C 3/095 (20060101); C03C 4/00 (20060101); C03C 3/093 (20060101)

Expiration Date: 8/08/02018