Patent ID: 8159907
Filing Date: 2012-04-17
Classification: G02B,G11B

Abstract:
1. An optical pickup device comprising: a laser light source; an objective lens which converges laser light emitted from the laser light source on a recording medium; a photodetector which receives the laser light reflected on the recording medium; an optical system which guides the laser light to the photodetector as convergent light; a light transmitting plate which is disposed between the optical system and the photodetector with an inclination with respect to an optical axis of the laser light to impart astigmatism to the laser light reflected on the recording medium; and an optical element which separates four light fluxes of the laser light from each other, the four light fluxes being obtained by dividing the laser light by two straight lines respectively in parallel to a first focal line direction and a second focal line direction, the first focal line direction being a direction of a first focal line of the laser light, the second focal line direction being a direction of a second focal line of the laser light and orthogonal to the first focal line direction, the first focal line and the second focal line being generated by the astigmatism imparted by the light transmitting plate.