Multi-Excitation-Mode Electromagnetic Tomography (EMT) System

Min He, Ze Liu, Lijun Xu and Ling-an Xu

Department of Automation, Tianjin University, Tianjin, 300072, P. R. China,hemin@eyou.com

ABSTRACT

A kind of Electromagnetic Tomography (EMT) system with multiple excitation modes was proposed and built. It could be used to compare the differences of these excitation modes and optimize the sensor design. A quasi-parallel excitation scheme which was implemented in this system was proved by experiments to be able to improve the quality of the reconstructed image because it could obtain more independent projections than the parallel mode and produces relatively more even sensitivity distribution than the coil-pair mode. In order to obtain both real and imaginary parts of measured signal an orthogonal demodulation method based on phase feedback searching was brought forward, and the real-time property of data acquisition especially of the signal demodulation process was improved and enhanced.

Keywords Electromagnetic Tomography, Sensor, Excitation System, Demodulation.