| 摘要 |
PURPOSE:To perform high resolution in high accuracy at a high speed by controlling a semiconductor laser with a current of the sum or difference of a control current of an optoelectric negative feedback loop, and a current generated by converting means. CONSTITUTION:A light emitting level command signal is input to a comparison amplifier 1 and a current converter 2, and part of the optical output of a driven semiconductor laser 3 is monitored by a photodetector 4. The amplifier 1, the laser 3 and the photodetector 4 constitute an optoelectric negative feedback loop, and the amplifier 1 compares a photodetection signal proportional to a photovoltaic current induced at the photodetector 4 with the light emitting level command. The forward current of the laser 3 is so controlled through a resistor 5 according to the result that a photodetection signal becomes equal to the light emitting level command signal. Thus, a high resolution can be preformed in high accuracy at a high speed. |
