Patent ID: 8358571
Filing Date: 2013-01-22
Classification: G11B

Abstract:
1. An optical pickup device, comprising: a light source which emits laser light; an objective lens which focuses the laser light on a recording layer; an astigmatism element which imparts astigmatism to reflected light of the laser light reflected on the recording layer; a spectral element into which the reflected light is entered, and which separates the reflected light; and a photodetector which receives the reflected light, wherein the astigmatism element converges the reflected light in a first direction and in a second direction perpendicular to the first direction so that the reflected light forms focal lines at different positions from each other, and the spectral element is divided into four third areas by a first area having a certain width and formed along a straight line in parallel to the first direction, and by a second area having a certain width and formed along a straight line in parallel to the second direction, the spectral element being configured to guide the reflected light passing through the four third areas to respective corresponding sensors on the photodetector while making propagating directions of the reflected light different from each other, and to avoid guiding the reflected light entered into the first area and into the second area to the sensors.