| 摘要 |
PURPOSE:To obtain a good focusing error signal, tracking error signal, and address signal or data signal with the aid of a simplified constitution, by providing a composite optical detector consisting of plural photoreceivers and processing circuits. CONSTITUTION:A light beam emitted from a semiconductor laser 501 is reflected on an optical recording medium 505, and a reflected light beam is made incident on a composite optical detector 507 through a beam splitter 503, etc., and a condenser lens 506. The detector 7 processes the outputs of the first and the second photoreceiving parts 101 and 102 at the first processing circuit 106, and obtains the focusing error signal, and also, obtains the tracking error signal by processing the outputs of the third and the fourth photoreceiving parts 103 and 104 at the second processing circuit 107. Also, the address signal or the data signal can be obtained by processing the output of the fifth photoreceiving part 105 at the third processing circuit 108. Thus, by providing the detector 507, the good focusing error signal, tracking error signal, and address signal or data signal can be obtained.
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