Imaging of steel reinforcement bars using planar electromagnetic induction tomography

Electromagnetic induction tomography (EMT) is a non-invasive imaging technique for determining the conductivity and magnetic permeability distributions in a region of interest (ROI), from measurement of inductances at its boundary. This paper describes how this technique may be used for imaging steel reinforcement bars embedded in a nonconducting and non-magnetic medium, from measurements made on only one side of the ROI. Reconstruction of the ROI is first carried out using the simultaneous increment reconstruction technique (STRT), which gives a crude estimate of the position and size of the reinforcement bars. These estimates are then refined using a non-linear reconstruction technique based on a parametric representation of the ROI.