| 摘要 |
PURPOSE:To measure a plurality of the distances highly accurately, by modulating electromagnetic waves whose wavelengths are 0.5mum or more and 5mum or less, by frequencies of 100kHz or more and 5MHz or less, and comparing the phase delays corresponding to the time length during which the electromagnetic waves go to and return from the object to be measured with a reference signal. CONSTITUTION:The electromagnetic waves, whose wavelengths are 0.5mum or more and 5mum or less, are generated by light emitting diode 2, and modulated by frequencies of 100kHz or more and 5MHz or less from an oscillator 1. Reference luminous flux 4a and reflected luminous flux 4c are received by light receiving elements 6 and 7. The phase is delayed in correspondence with the time length during which the electromagnetic waves go to and return from the object to be measured. The phase delays corresponding to the distances 2m, 5m, and 8m are imparted to reference signal generating means 101-10n. The outputs from phase difference detectors 111-11n become the voltages corresponding to the phase differences between the reference signal and the measured signal. When both distances are agreed, the outputs become zero. This fact is detected by zero detectors 12, and converted by a signal converting means 13 as a distance signal, and displayed by a display 14. Therefore the distances of 2m, 5m, and 8m can be measured accurately. |
