Patent ID: 8400901

Claim:
An optical pickup device, comprising: a laser light source; an objective lens which focuses laser light emitted from the laser light source on a recording medium; an astigmatism element into which the laser light reflected on the recording medium is entered, and which converges the laser light in a first direction for generating a first focal line and converges the laser light in a second direction perpendicular to the first direction for generating a second focal line; a photodetector which receives the laser light passing through the astigmatism element; and a light separating element into which the laser light reflected on the recording medium is entered, and which guides the laser light entered into two first areas and into two second areas to four positions different from each other, on a light receiving surface of the photodetector, wherein the photodetector has a plurality of sensing portions disposed at the four different positions, when an intersection of two straight lines respectively extending in parallel to the first direction and the second direction and intersecting with each other is aligned with an optical axis of the laser light, the two first areas are disposed in a direction along which one pair of vertically opposite angles defined by the two straight lines are aligned, and the two second areas are disposed in a direction along which another pair of vertically opposite angles are aligned, and the light separating element imparts a light separating function to the laser light entered into the two first areas in directions identical to each other and with magnitudes different from each other, and imparts a light separating function to the laser light entered into the two second areas in directions identical to each other and with magnitudes different from each other.