| 摘要 |
PURPOSE:To surely hold the light quantity of each light beam in a multibeam system at a prescribed value by dividing the output signal of a light-receiving means for monitoring according to the output ratio of plural light-receiving outputs for processing signals and driving the light beam based on the result of division. CONSTITUTION:Light beams LA and LB emitted from plural beam light sources 11A and 11B are received at a light-receiving means 20 for monitoring, and an output signal SPD1 according to the sum of the light quantities of both beams is sent. The light beams LA and LB are made incident on two light-receiving means for processing signals including photodetectors to detect respective light quantities, and consequently, first and second light-receiving output signals SRFA and SRFPB for processing signals are sent. The output signal SPD1 of the light-receiving means 20 for monitoring is divided according to the output ratio of the light-receiving output signals SRFA and SRFB for processing signals, and a control is executed so as to hold respective light beams LA and LB at prescribed light quantities based on division results SPDA and SPDB. |
