| 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 current converter 2 outputs a current preset according to a light emitting level command signal (a current preset based on the optical output-forward current characteristic of a semiconductor laser 3 and coupling coefficient of a photodetector 4 and the laser 3, and optical input-photodetecting signal characteristic of the photodetector 4) so that the photodetecting signal becomes equal to the light emitting level command signal. A current of the sum of the output current of the converter 2 and a control current output from a comparison comparator 1 becomes a forward current of the laser 3. Thus, a high resolution can be preformed in high accuracy at a high speed. |
