Patent ID: 8264937

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 to generate a first focal line and converges the laser light in a second direction perpendicular to the first direction to generate a second focal line; a spectral element into which the laser light reflected on the recording medium is entered, and which makes propagating directions of light fluxes entered into first through fourth areas different from each other to disperse the four light fluxes from each other; and a photodetector which receives the dispersed light fluxes to output a detection signal, wherein assuming that an intersection of first and second straight lines respectively in parallel to the first direction and the second direction and perpendicularly intersecting with each other is aligned with a center of the spectral element, the first and second areas are disposed in a direction along which a pair of vertically opposite angles defined by the first and second straight lines are aligned, and the third and fourth areas are disposed in a direction along which the other pair of vertically opposite angles defined by the first and second straight lines are aligned, the astigmatism element is disposed at such a position that the direction along which the first and second areas are aligned is in parallel to a direction of a track image of the recording medium projected onto the spectral element, each of the first and second areas has a surface area larger than a surface area of each of the third and fourth areas, and a boundary portion between the first and second areas, and the third and fourth areas includes a straight portion extending in a direction perpendicular to the direction of the track image.