OPTICAL RANGE MEASUREMENT TYPE BODY DETECTING DEVICE

摘要

PURPOSE:To remove the influence of the reflection factor of a body to be detected and to prevent the generation of wrong information by detecting the range up to the objective body from the phase difference between reference light and detection light. CONSTITUTION:The reference light and signal light photodetected by photodiodes 18 and 19 while an optical system including a half-mirror are amplified by amplifying parts 21 and 22 and inputted to mixing parts 23 and 24, and they are mixed with a signal sent out of the same local oscillation part 25 to perform frequency conversion. The resulting signals are passed through filter parts 26 and 27 to remove noise components and further outputted as rectangular waves through waveform shaping parts 28 and 29. Those outputs are inputted to a gate part 30 to generate a pulse with width from the leading edge of the signal corresponding to the reference light to the leading edge of the signal corresponding to the signal light. Clock signals from a clock generating part 31 are outputted by as many as the output pulse width of the gate part 30 and inputted to a counter part 32, and consequently the signal proportional to the phase difference between the reference light and signal light is detected.