Patent ID: 8064317
Filing Date: 2011-11-22
Classification: G11B

Abstract:
1. An optical pickup apparatus, comprising: a laser light source; an objective lens for converging the laser light emitted from the laser light source on a recording medium; an astigmatic element for introducing astigmatism to the laser light reflected by the recording medium so as to alienate a first focal line position occurring due to convergence of the laser light in a first direction and a second focal line position occurring due to convergence of the laser light in a second direction vertical to the first direction from each other in an advancing direction of the laser light; an optical element for varying advancing directions of luminous fluxes within four different luminous flux regions with one another, out of the laser light reflected by the recording medium, so as to scatter the luminous fluxes within the four luminous flux regions with one another; and a photodetector for receiving each of the scattered luminous fluxes so as to output a detection signal; wherein when an intersecting point of two mutually crossing straight lines respectively parallel to the first direction and the second direction is aligned to an axis of the laser light, the two luminous flux regions are placed in a direction where a set of vertical angles created by the two straight lines forms a line, and the remaining two luminous flux regions are placed in a direction where the other set of vertical angles forms a line.