Yin, Wuliang and Peyton, A. J. and Dickinson, Stephen J. (2004) Simultaneous measurement of distance and thickness of a thin metal plate with an electromagnetic sensor using a simplified model. IEEE Transactions on Instrumentation and Measurement, 53 (4). pp. 1335-1338. ISSN 0018-9456
Abstract
This paper presents a simplified model which can describe the inductance change when an air-core coil is placed next to a thin nonmagnetic metallic plate. The model has two independent parameters and is valid for a range of thickness, conductivity, and lift-offs. Use of this new relationship provides a fast and accurate method to measure the distance and thickness simultaneously. Measurements made for a sample coil next to thin copper and aluminum plates of various thicknesses verified the theory and the proposed method.