| 摘要 |
PURPOSE: To correct an angle of a transmission light without hindrance practically even when a background light is considerably increased. CONSTITUTION: A received light from an opposite transmitter is received by plural detection elements 19a-19d and converted into a current signal, and converted into a voltage signal by load impedance sets 21a-21d. The voltage signal is divided into two, and they pass through band pass filters 22a-22d including a frequency of a pilot signal of an opposite transmitter for its pass band and band pass filters 24a-24d not including the frequency of the pilot signal of the opposite transmitter for its pass band. The signals are detected by detectors 24a-24d and 25a-25d, from which detection signals Va-Vd, Va'-Vd' are obtained. A cut-off frequency of the servo system loop filter is varied based on the detection signals Va-Vd, Va'-Vd' to correct an angle of a light transmission section. |
