| 摘要 |
<p>Disclosed is an optical glass which is excellent in devitrification characteristics and press moldability during high temperature molding and enables to reduce weight/size of an optical system.Specifically disclosed is an optical glass containing, in mass% in terms of oxides, 10-25% of B<SUB>2</SUB>O<SUB>3</SUB>, 0.5-12% of SiO<SUB>2</SUB>, 17-38% of La<SUB>2</SUB>O<SUB>3</SUB>, 5-25% of Gd<SUB>2</SUB>O<SUB>3</SUB>, 8-20% of ZnO, 0.5-3% of Li<SUB>2</SUB>O, 5-15% of Ta<SUB>2</SUB>O<SUB>5</SUB> and 3-15% of WO<SUB>3</SUB>. In this optical glass, the mass ratio of the total amount of SiO<SUB>2</SUB> and B<SUB>2</SUB>O<SUB>3</SUB> to the total amount of ZnO and Li<SUB>2</SUB>O, namely (SiO<SUB>2</SUB> + B<SUB>2</SUB>O<SUB>3</SUB>)/(ZnO + Li<SUB>2</SUB>O), is within the range of 1.35-1.90.</p> |
