| 摘要 |
PURPOSE:To reduce the time delay of a photodetecting element and to improve frequency responsiveness by forming spare slits in a movable slit plate and a fixed slit plate arranged between a light emitting and a photodetecting element in addition to regular slits. CONSTITUTION:The movable slit plate 7 and fixed slit plate 8 are provided between the light emitting element 2 and photodetecting element 9 to constitute a pulse generator. Then, the spare slits 11 and 12 for making light incident on the photodetecting element 9 previously and the regular slits 6 and 8a for making light incident on the photodetecting element 9 regularly are formed in the slit plates 7 and 8. Consequently, some light is made incident on the photodetecting element 9 previously before its quantity of photodetection attains to its peak, so the frequency responsiveness is improved greatly and the setting of a threshold level is easily adjusted. |
