| 摘要 |
An optical head includes a (1) light radiating unit in which the relative positions of first and second light sources are set so that a straight line interconnecting a spot position of the laser light illuminated on an optical disc and a spot position of the second laser light similarly illuminated on the optical disc will be 45±15° with respect to a recording track on the optical disc and (2) a light receiving element having plural light receiving sections arranged substantially parallel to a splitting line substantially parallel to the straight line which interconnects the spot position of the laser light illuminated on an optical disc and the spot position of the second laser light similarly illuminated on the optical disc and which is projected on the optical disc. Each of the light receiving sections is split into four portions by a splitting line substantially parallel to the recording track on a signal recording surface of the optical disc and by a splitting line substantially perpendicular to it. With this configuration, focusing error signals can be properly detected by the astigmatic method in an optical head adapted for coping with plural optical heads of different kinds, while the head can be reduced in size.
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