| 摘要 |
PURPOSE:To read out a bit of recording information without saturating a signal detecting amplifier, by connecting in series a pair of photodetectors having photoelectric conversion functions in the direction of same polarity, and taking out a signal current equivalent to the difference of incident light quantities. CONSTITUTION:A magneto-optical pickup 13 is arranged oppositely to a magneto-optical disk 12 to be rotary-driven. A laser diode 15 is contained in the pickup 13, and an emitted laser beam is projected on the recording film 12a of the disk 12 through an objective lens 19. Reflected light is received at photodiodes (PD) 32A and 32B which form a signal detection circuit 31 passing through beam splitters 18 and 21, and analyzers 27A and 27B. The PDs 32A and 32B are connected in series in the direction of the same polarity, and the signal current equivalent to the difference of the incident light quantity from a connecting point connected in series, is taken out, and is inputted to an amplifier 33. The amplifier 33 converts and outputs the signal current to a voltage. Thus, it is possible to read out the bit of recording information without saturating the signal detecting amplifier. |
