Patent ID: 7239596

Claim:
An optical pickup device which selectively records or reproduces data on or from a first optical recording medium, a second optical recording medium having a recording density lower than that of the first optical recording medium and having a substrate thickness larger than that of the first optical recording medium, and a combined optical recording medium including combined and integrally stacked signal surfaces of the first and second optical recording mediums, the device comprising: a first laser light source which emits a first laser light having a wavelength of 450 nm or less for the first optical recording medium; a second laser light source which emits a second laser light having a wavelength longer than that of the first laser light for the second optical recording medium; an objective lens whose numerical aperture (NA) is set to 0.75 or more for the first optical recording medium and in which at least one of first and second surfaces turning to a reverse direction each other is formed in a non-spherical surface and which converges the first and second laser lights on the respective signal surfaces of the first and second optical recording mediums; and an aberration correction element in which a circular light-transparent flat portion and an annular aperture limiting portion for the second laser light are formed toward an outer circular portion from a central portion on the side of the first and second laser light sources and in which a diffraction pattern portion is formed in an inner circular region on the side of the objective lens and in which an outer side of the diffraction pattern portion is flatted, wherein the aberration correction element transmits the first laser light, which is incident thereon in a parallel light state, as such through the light-transparent flat portion and the aperture limiting portion for the second laser light, transmits the first laser light without diffracting the first laser light through the diffraction pattern portion, and allows a 0-order light thereof to be incident upon the objective lens, and the aberration correction element interrupts the second laser light, which is incident thereon in the parallel light state, by the aperture limiting portion for the second laser light to limit the numerical aperture into the objective lens to a predetermined numerical aperture, transmits the second laser light through the light-transparent flat portion, and thereafter diffracts the second laser light by the diffraction pattern portion so that a 1st order light of the second laser light capable of correcting a spherical aberration that will occur on the objective lens is incident upon the objective lens.