PURPOSE: To accurately detect laser light even if the intensity of the light is varied and to detect its scan starting time point by controlling the output pulse width of a timer for generating a synchronizing pulse at the maximum value of an integrated value varied in response to the intensity of the light.
CONSTITUTION: An output pulse signal from an optical detector 1 is input to a waveform shaper 2, and input to an integrated 3 as a waveform-shaped pulse signal; a voltage output proportional to the width of the generated input pulse is input to a peak holding circuit 4, which holds its peak value, and the held value is applied to a timer 6. On the other hand, an output from the shaper 2 is also input to a delay circuit 5, delayed for a longer time than the pulse width time to be presumed of the pulse output from the shaper 2, and input to the trigger terminal of the timer 6. Thus, a pulse having a width corresponding to the width of the pulse output from the shaper 2 is generated from the timer 6 to be used as a synchronizing signal.
NAGASAWA KIYOTO
MAMA TAKASHI
FUJIOKA NAONOBU
KANEKO YOSHIO
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