Patent ID: 7490485

Claim:
A process for producing an optical element, which comprises softening a press-molding glass gob under heat and press-molding it, said press-molding glass gob consisting of an optical glass comprising, by weight %, 2 to 45% of B 2 O 3 , 0 to 30% of SiO 2 provided that the content of B 2 O 3 >the content of SiO 2 , 10 to 50% of La 2 O 3 , 0 to 30% of TiO 2 , 0 to 15% of ZnO, 0 to 15% of ZrO 2 , 0 to 35% of Nb 2 O 5 , 0 to 35% of BaO, 0 to 5% of SrO, 0% or more but less than 8% of CaO, 0% or more but less than 13% of MgO, provided that the total content of BaO, SrO, CaO and MgO is 0 to 40%, 0 to 20% of Gd 2 O 3 , 0 to 15% of Y 2 O 3 , 0 to 18% of Ta 2 O 5 , 0% or more but less than 0.5% of WO 3 , 0% or more but less than 1.5% of a total of Na 2 O, K 2 O and Li 2 O, 0 to 10% of GeO 2 , 0 to 20% of Bi 2 O 3 , 0 to 10% of Yb 2 O 3 , 0 to 10% of Al 2 O 3 , 0% or more but less than 2% of Sb 2 O 3 and 0 to 1% of SnO 2 and having an Abbe's number (νd) of 20 to 40.