A Non-Contact Micro-Displacement Meter

A method capable of detecting microinch displacements of a transducer surface vibrating in the fractional megacycle range has been developed. The dynamic displacements of a vibrating transducer are detected with the aid of a specialized frequency modulation system. The vibrating transducer face is incorporated into the system in a manner such that the center frequency of an oscillator is varied in accordance with the transducer vibrations. The frequency modulation system transforms the frequency, deviations into a corresponding amplitude varying signal. In this way, accurate measurements of transducer vibrations can readily be obtained. The system is inherently capable of detecting transducer displacements with equal facility in either air or a viscous fluid.