Patent ID: 6950384

Claim:
An optical pickup apparatus for recording and/or reproducing information for an optical information medium, comprising: a first light source configured to emit a first light flux having a first wavelength for recording and/or reproducing a second information recording medium provided with a transparent substrate; 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 a first information recording medium provided with a transparent substrate; 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 information recording medium provided with a transparent substrate having a thickness thicker than that of each of the first and second information recording mediums; and an objective lens configured to converge the first, second, and third light fluxes onto the second, first, and third optical information recording mediums respectively, the objective lens comprising an aspherical refractive surface and a ring-shaped diffractive portion; wherein when recording and/or reproducing information is conducted for the second information recording medium, the first light flux emitted from the first light source enters the objective lens as a parallel light flux and is converged on the second information recording medium, when recording and/or reproducing information is conducted for the first information recording medium, the second light flux emitted from the second light source enters the objective lens as a parallel light flux and is converged on the first information recording medium, when recording and/or reproducing information is conducted for the third information recording medium, the third light flux emitted from the third light source enters the objective lens as a parallel light flux and is converged on the third information recording medium, and wherein the aspherical refractive surface and the ring-shaped diffractive portion correct spherical aberrations due to difference in wavelenath among the first, second, and third light fluxes and spherical aberration due to difference in thickness of the transparent substrate among the first, second, and third optical information medium.