MAGNETO-OPTICAL SIGNAL DETECTION CIRCUIT

PURPOSE:To simplify a detection circuit and to decrease low noise amplifiers to one by connecting two photodetectors in series and impressing voltage on both ends of the photodetectors. CONSTITUTION:Two photodetectors 13 and 14 are connected in series, and potential Vs higher than reference potential Ve is impressed on the cathode of the photodetector 13 and the potential Ve is impressed on the anode of the photodetector 14. By making separation light projected from a polarized light beam splitter incident on the two photodetectors 13 and 14 respectively, the differential output of both photodetectors is obtained on both ends of the photodetector 14. The differential output is amplified by the low noise amplifier 15 so as to detect a magneto-optical signal recorded on a magneto-optical recording medium. In the above-mentioned constitution of the circuit, two low noise amplifiers are decreased to one. Also, a differential amplifier is not needed.