Patent ID: 7141524

Claim:
A lead-free optical glass having a refractive index n d of 1.55≦n d ≦1.60, an Abbe number V d of 54≦V d ≦63 and a transformation temperature Tg≦500° C., wherein said glass Is free of Li 2 O, free of CuO and comprises a composition, in percent by weight, based on oxide content, of: P 2 O 5 43–56 ZnO 21–36 Al 2 O 3 0–6 Na 2 O 0.5–16 K 2 O 0–8 ΣM 2 O ≦16 MgO 0–5 CaO 0–5 BaO 3–14 B 2 O 3 0–8 La 2 O 3 0–7, wherein ΣM 2 O is a sum total amount of all alkali metal oxides present.