| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide an objective lens capable of converging a laser beam on an information recording surface while aberration is reduced as far as possible for each of two or more kinds of optical disks having different thicknesses of a transparent substrate, an optical head, an optical system and a design method of the objective lens. <P>SOLUTION: The objective lens 5 is used in the optical head for which a distance between a DVD laser 1 and a CD laser 2 is fixed. The objective lens 5 converges the laser beam emitted from the DVD laser 1 to a DVD 6 by a numerical aperture 0.60 and converges the laser beam emitted from the CD laser 2 to a CD 7 by the numerical aperture 0.47. In this case, the wavefront aberration D2 on design relating to the CD is made larger than the wavefront aberration D1 on the design relating to the DVD. <P>COPYRIGHT: (C)2007,JPO&INPIT |
