Patent ID: 7582579

Claim:
A phosphate optical glass comprising, as glass components by mass %, from 1 to 4 mass % of Li 2 O, 73 to 85 of P 2 O 5 , from 14 to 26 of Al 2 O 3 , from 1 to 12 of K 2 O+Li 2 O, from 0 to 12 of SiO 2 , from 0 to 12 of B 2 O 3 , from 0 to 12 of Na 2 O, from 0 to 12 of Y 2 O 3 , from 0 to 12 of La 2 O 3 , from 0 to 12 of MgO+CaO+SrO+BaO, from 0 to 10 of ZrO 2 +TiO 2 +Gd 2 O 3 , from 0 to 10 of Ta 2 O 5 +GeO 2 +Ga 2 O 3 +Nb 2 O 5 +WO 3 +TeO 2 , from 0 to 2 of Sb 2 O 3 , and from 0 to 12 of ZnO+PbO and which has a glass transition point (Tg) of at most 600° C.