| 摘要 |
PURPOSE:To avoid the noise of a semiconductor laser, by providing a comparison circuit rectifying a generated noise and inverting its output with the rectified output and a circuit stopping the noise detection for a prescribed period after an output of the comparison circuit is inverted. CONSTITUTION:The noise signal after passing through a high pass filter is amplified as an amplifier 8. Then, the signal is rectified at a full-wave rectifier circuit 9. There exist various noise waveforms and the noise has no constant waveform, the noise may or may not be detected at a half-wave rectifier circuit. The noise signal is full-wave-rectified, compared at a comparison circuit 10, where an output of a high or low level is obtained with a rectified voltage level. Every time a monostable mltivibrator 11 is operated, the output is inverted. This output switches a changeover switch 13. When the changeover switch 13 is opened, a reference voltage of a comparison circuit 5 depends on 4A, 4C and a light emitting diode 1A is driven so as to obtain an optical output corresponding to the reference voltage. |
