| 摘要 |
An optical pickup device imparts different astigmatisms from each other to light fluxes in four light flux areas A through D formed around an optical axis of laser light, out of the laser light reflected on a disc. The optical pickup device also changes the propagating directions of the light fluxes in the light flux areas A through D to separate the light fluxes in the light flux areas A through D from each other. A signal light area where only signal light exists is defined on a detection surface of a photodetector. Sensing portions are arranged at a position corresponding to the signal light area. Accordingly, only the signal light is received by the sensing portions, thereby suppressing deterioration of a detection signal resulting from stray light.
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