ELECTROMAGNETIC INDUCTANCE TOMOGRAPHY (EMT) - SENSOR, ELECTRONICS ANDIMAGE-RECONSTRUCTION ALGORITHM FOR A SYSTEM WITH A ROTATABLE PARALLELEXCITATION FIELD

The main features and principle of operation of an electromagnetic ind uctance tomography system are described. The system can image the dist ribution of electrically conducting and/or magnetically permeable mate rials and is analogous to the other electrical tomography systems whic h measure capacitance or resistance, The paper presents a nonintrusive system with a rotatable parallel uniform excitation magnetic field wh ich improves the detectability at the centre of the abject space with respect to that near the periphery. The sensor construction, electroni cs design and image reconstruction are described, A novel electronic c ompensation scheme is used to condition the output signals from the se nsor, This scheme subtracts the empty space background field measureme nts and consequently increases the overall dynamic range of the data a cquisition system, An image reconstruction technique based on a correl ation method is described and some images are presented.