| 摘要 |
PURPOSE:To measure the displacement of the vibrations in broad range from a low frequency to a high frequency highly accurately with good response, by transmitting a sound wave to the vibrating body to be measured, and detecting the phase difference between the transmitted sound wave and the received sound wave. CONSTITUTION:On the required surface of a vibrating table 10, a transmitting device 12 which transmits the sound wave from a sound wave oscillator 11 and a sound wave receiving device 14 which transduces the reflected sound wave into the electric signal are provided. They are connected to a phase difference meter 13, respectively. When the vibrating table 10 is vibrated in the progressing direction of the sound wave, the phase difference is generated between the transmitted sound wave and the received sound wave. The phas difference theta is expressed by DELTAtheta=DELTAx/lambda.2pi where lambda is a wavelength and DELTAx is the amount of displacement. Said phase differnce is detected by a phase difference meter 13 and a phase-voltage converter 15. The amount of displacement DELTAx of the vibrating table 10 can be measured highly accurately in the reserse order with good response. When the wavelength is changed, the measuring range for the small displacement and the large displacement can be changed. |
