| 摘要 |
PURPOSE:To stabilize the output of a photodetector by involving and adding respective output signals of plural photodetectors arranged with prescribed phase differences and controlling the quantity of emitted light of light emitting elements so that this sum voltage is a certain value. CONSTITUTION:Output signals having a prescribed phase difference from plural, for example, two photodetectors 6 and 7 are squared by square operators 10 and 11 and are added by an adder 12, and the output voltage is compared with a reference voltage E of a reference voltage source 15 by an amplifier 14 with a feedback resistance 13, and light emitting elements 4 and 5 are connected to the output side of the amplifier 14, and the quantity of emitted light of elements 4 and 5 is so controlled that said output voltage is equal to the voltage E. Thus, variance of elements 6 and 7, variance of the quantity of emitted light of elements 4 and 5, etc. are eliminated. |
