| 摘要 |
PROBLEM TO BE SOLVED: To provide optical glass having a refractive index (n) and an Abbe number (&ngr;) within expected range, applicable preferably to correcting chromatic aberration, and having high devitrification resistance, and to provide a lens preform using the same.SOLUTION: This optical glass includes, in terms of mass%, a 5.0-55.0% BOcomponent and a 10.0-55.0% LaOcomponent, to the whole glass mass of the composition in terms of oxides, and further includes an AlOcomponent and an F component. The optical glass has a refractive index (n) over 1.57 and an Abbe number (&ngr;) over 50. |
