| 摘要 |
<p>Disclosed are: an optical glass which has a refractive index (nd) and an Abbe's number (?d) that fall within predetermined ranges and also has a small relative partial dispersion (?g, F); and a lens preform which is produced using the optical glass. The optical glass contains an SiO2 component as an essential component, additionally contains at least any one component selected from an Nb2O5 component, a TiO2 component, a ZrO2 component, a Ta2O5 component and a WO3 component, and has a refractive index (nd) of 1.78 or more and an Abbe's number (?d) of 30 or less, wherein the relative partial dispersion (?g, F) and the Abbe's number (?d) of the optical glass fulfill the relationship represented by formula: (-1.60×10-3×?d+0.6346) = (?g, F) = (-4.21×10-3×?d+0.7207) when ?d falls within the range of 25 or less (i.e., ?d = 25) and fulfill the relationship represented by formula: (-2.50×10-3×?d+0.6571) = (?g, F) = (-4.21×10-3×?d+0.7207) when ?d falls within the range of more than 25 (i.e., ?d > 25).</p> |
