| 摘要 |
<p>An optical glass having optical constants of a refractive index (nd) of 1.78 or over, an Abbe number (½d) of 30 or below, and a partial dispersion ratio (¸g, F) of 0.620 or below comprises SiO 2 and Nb 2 O 5 as essential components, wherein an amount of Nb 2 O 5 in mass % is more than 40%. The optical glass further comprising, in mass % on oxide basis, less than 2% of K 2 O and one or more oxides selected from the group consisting of B 2 O 3 , TiO 2 , ZrO 2 , WO 8 , ZnO, SrO, Li 2 O and Na 2 O wherein a total amount of SiO 2 , B 2 O 3 , TiO 2 , ZrO 2 , Nb 2 O 5 , WO 3 , ZnO, SrO, Li 2 O and Na 2 O is more than 90% and TiO 2 /(ZrO 2 + Nb 2 O 5 ) is less than 0.32.</p> |
