Patent ID: 8288299

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 20 percent; ZnO 0 to 20 percent; ZrO 2 0 to 4.5 percent; TaO 2.5 0 to 7 percent; YbO 1.5 0 to 0.5 percent; GeO 2 0 to 5 percent; YO 1.5 0.5 to 10 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 the ZnO content, three times the ZrO 2 content, and five times the TaO 2.5 content (ZnO+3ZrO 2 +5TaO 2.5 ) being 40 percent or less; the combined sum of twice the LiO 0.5 content, the ZnO content, and Â½ the F content (2LiO 0.5 +ZnO+(F/2)) when the total quantity of cations is denoted as 100 being 20 percent or greater; the value of B B â€”(B O â€”B B ) falling within a range of âˆ’60 to +20, 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 1.75 to 1.81; the AbbÃ© number Î½d being 48 to 52; and the glass transition temperature Tg being 590Â° C. or lower.