Patent ID: 8575047

Claim:
An optical glass comprising, denoted as cationic percentages: BO 1.5 20 to 70 percent; LaO 1.5 6 to 30 percent; GdO 1.5 4 to 25 percent; SiO 2 0 to 20 percent; LiO 0.5 0 to 10 percent; ZnO 0 to 28 percent; ZrO 2 0 to 8 percent; TaO 2.5 0 to 10 percent; TiO 2 0 to 8 percent; NbO 2.5 0 to 8 percent; WO 3 0 to 10 percent; YbO 1.5 0 to 3 percent; GeO 2 0 to 5 percent; as well as O and F, with the F/O molar ratio of the F content to the O content being 0.01 to 0.30; the combined sum of twice the LiO 0.5 content, the ZnO content, and ½ the F content (2LiO 0.5 +ZnO+(F/2)) when the total quantity of cations is denoted as 100 being 26 percent or greater; the value of twice the LiO 0.5 content divided by the combined sum of twice the LiO 0.5 content and the ZnO content (2LiO 0.5 /(2LiO 0.5 +ZnO)) being 0.7 or less; the combined sum of the ZnO content, three times the ZrO 2 content, and 5 five times the TaO 2.5 content (ZnO+3ZrO 2 +5TaO 2.5 ) being 55 percent or less; the value of B B —(B O —B B ) falling within a range of −60 to 0, with the value B B being 1.5 times the content of BO 1.5 denoted as a cationic percentage, the total quantity of all cations in the glass being denoted as 100, and the molar ratio of the total oxygen content relative to this total quantity being denoted as B O ; the refractive index nd being 1.825 to 1.90; the Abbé number vd being 35 to 43; the degree of the refractive index and dispersion represented by nd−(2.25−0.01×vd) being 0.009 or greater; and the glass transition temperature Tg being 570° C. or lower.