Patent ID: 7670973

Claim:
A lead-free and arsenic-free optical glass with a refractive index n d of 1.91≦n d ≦2.05 and an Abbe number ν d of 19≦ν d ≦25, wherein said optical glass having a composition consisting essentially, in percent by weight based on oxide content, of: Bi 2 O 3 55-70 GeO 2 13-21 SiO 2 0.5-9 B 2 O 3 0-10 Li 2 O 0-5 Na 2 O 0-5 K 2 O 0-5 Cs 2 O 0-5 MgO 0-10 CaO 0-10 SrO 0-10 BaO 0-10 ZnO 0-10 TiO 2 0-5 La 2 O 3 0-7 WO 3 0-6 Nb 2 O 5 0-6 Σ alkali metal oxides 0-5 Σ alkaline earth metal oxides 0-10 ΣLa 2 O 3 , WO 3 , Nb 2 O 5 , TiO 2 0-8 at least one fining agent 0-2, wherein a ratio of said Bi 2 O 3 to said GeO 2 is less than or equal to 5.