Patent ID: 8228778
Filing Date: 2012-07-24
Classification: G11B

Abstract:
1. An optical pickup device for irradiating laser light onto a recording medium having a plurality of recording layers, comprising: a light source for emitting laser light; an objective lens for converging the laser light on the recording medium; an astigmatism portion into which the laser light reflected on the recording medium is entered, and which is provided with a plurality of lens areas formed around an optical axis of the laser light to impart astigmatism to the laser light individually with respect to each of the lens areas, the lens areas being divided by at least two straight lines each having an angle of 45 degrees with respect to a track image from the recording medium; a light flux separating portion for making propagating directions of a light flux of the laser light to be entered into each of the lens areas different from each other to separate the light fluxes from each other; and a photodetector for receiving the separated light fluxes to output a detection signal.