| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide an optical system for an optical disk suitable for recording or reproducing of information on the optical disk having a high recording density, wherein off-axis aberration generated during recording or reproducing of information, particularly astigmatism, can be preferably suppressed even without a coupling lens. <P>SOLUTION: The optical system for the optical disk includes a light source and an objective lens satisfactorily imaging light emitted from the light source on a recording surface of the optical disk, wherein the coupling lens is dispensed with between the light source and the objective lens. A condition -0.70≤d'/(ML')≤-0.57 is satisfied, wherein d' (mm) is a central thickness of the objective lens in terms of air equivalence, M is imaging magnification of the optical system, and L'm is an object-image distance in terms of air equivalence. <P>COPYRIGHT: (C)2008,JPO&INPIT |
