Patent ID: 7916612

Claim:
An optical pickup apparatus, comprising: a laser light source; an objective lens for converging a laser light emitted from the laser light source on a recording medium; an astigmatic element for introducing an astigmatism into the laser light reflected by the recording medium so that a first focal line position occurring by the convergence of the laser light in a first direction and a second focal line position occurring by the convergence of the laser light in a second direction vertical to the first direction are mutually spaced in a propagation direction of the laser light; an angle adjusting element for mutually contradicting propagation directions of luminous fluxes, out of the laser light reflected by the recording medium, within four different luminous flux regions so that the luminous fluxes within the four luminous flux regions are mutually dispersed; a photodetector for outputting a detection signal when receiving each of the dispersed luminous fluxes; and a polarization adjusting element for adjusting a polarization direction of the luminous fluxes within the four luminous flux regions; wherein when an intersection point of two mutually crossing straight lines respectively parallel to the first direction and the second direction is matched to an optical axis of the laser light, the angle adjusting element sets the four luminous flux regions so that two of the luminous flux regions are placed in a direction in which a set of opposite angles made by the two straight lines are aligned and remaining two luminous flux regions are placed in a direction in which an alternate set of opposite angles are aligned, and the polarization adjusting element mutually differentiates polarization directions of luminous fluxes which are selected out of the luminous fluxes within the four luminous flux regions and which are adjacent in a peripheral direction in which the optical axis of laser light serves as an axis.