Patent ID: 7164625
Filing Date: 2007-01-16
Classification: G11B

Abstract:
1. An optical pickup apparatus for recording and/or reproducing information for a first, second and third optical disk provided with a transparent substrate, comprising: a first light source configured to emit a first light flux having a first wavelength for recording and/or reproducing information for a second optical disk which is a high density optical disk used with a blue laser beam; a second light source configured to emit a second light flux having a second wavelength longer than the first wavelength, for recording and/or reproducing information for a first optical disk; a third light source configured to emit a third light flux having a third wavelength longer than the second wavelength, for recording and/or reproducing a third optical disk; and an objective lens having an aspherical refractive surface and a ring-shaped diffractive surface designed with a phase difference function such that spherical aberrations of the first, second and third light fluxes due to difference in thickness of the transparent substrate among the first, second and third optical disks are corrected.