| 摘要 |
<P>PROBLEM TO BE SOLVED: To reduce an aberration generated in optical disks with different substrate thicknesses for each light source while using a common objective lens by correcting two optical phases, respectively. <P>SOLUTION: Light from an optical system 8 using a red laser beam as a light source is transmitted through a beamsplitter 2, is reflected by a reflecting mirror 3 and transmitted through a transparent substrate 4 and the objective lens 6 which are fixed to a lens holder 5, is condensed with the objective lens 6 and is converged on the signal surface 7a of an optical disk substrate 7 with a thickness of about 0.6 mm. Light from an optical system 1 using the laser beam of a infrared color as a light source is reflected by a beamsplitter 2, reflected by the reflecting mirror 3, and then converged on the signal surface 9a of an optical disk substrate 9 with a thickness of about 1.2 mm. Optical retardation films 4a and 4b are formed on transparent substrate 4, and the films form level differences of depth d at positions of radii r0 to r7. <P>COPYRIGHT: (C)2003,JPO |
