Consideration on Measurement of Small Displacement with Non-Contact Method

Abstract

The auther studied a non-contact method of measuring a small displacement from about 10^-4 to 10^-2cm. The diaphragm of a special condenser type electroacoustical transducer is closely fixed near the measured object so that there exists between the diaphragm and the surface of object a thin air layer, the damping effect of which on the diaphragm changes with the thickness of layer, being accompanied by a change in amplitude of the diaphragm. The relation between the thickness of layer and the amplitude has theoretically been studied, and the calculation of an example and its characteristics are given.