| 摘要 |
<p>An objective lens for recording and/or reproducing information of an optical information recording medium, comprises at lest one aspherical surface. The objective lens is a single lens and satisfies the following formulas: 0.85 < NA < 0.98 0.80 < d/f < 3.00 0.5 < ¦1 < 5.8 where
NA is an optical information recording medium side numerical aperture,
d is a thickness (mm) on an optical axis,
f is a focal length (mm) for an object locating at an infinite distance, and
¦1 is an effective diameter (mm) of a light source side surface.</p> |
