International Society for Industrial Process Tomography

Magnetic Induction Tomography for imaging defects
and deformations of external surfaces

Victor Odedo^1*, Manuchehr Soleimani¹ and Stefano Spagnul²

¹Tomography Research Institute,University of Bath, Somerset, United Kingdom

²Product Division,Ergolines Lab, Trieste, Italy

^*Email: v.c.odedo@bath.ac.uk

ABSTRACT

Magnetic induction Tomography is a tomographic technique that is capable of imaging the passive electromagnetic properties of a target. Magnetic induction Tomography is a contactless and non-invasive technique which involves evaluating the electromagnetic field of the target. Steel production is among a growing number of applications that require a contactless method for remotely monitoring the process particularly due to the opaque nature of the structures and the high temperatures of molten steel. Magnetic induction Tomography is conventionally used in steel production to monitor the internal solidification process by imaging the conductivity of the area of interest. Here however we propose a Magnetic induction Tomography algorithm for imaging defects and deformations of external surfaces. We consider a metal square and utilise the Total Variation reconstruction algorithm for imaging, due to its robustness. We propose a threshold-differencing algorithm which involves subtracting an image of the perfect metal square with no deformations or defects from the image obtained for a metal square with deformations. We show that the image of the deformed square metal obtained using the Total Variation algorithm does not give a conclusive image of the surface deformation. However, by subtracting the image of a perfect square metal from the image of a deformed square metal we obtain a differential image which gives the information that the deformation contributes to the image of a perfect square metal. We show that we may obtain a conclusive image of the surface deformation by thresholding the differential image and combining it with the image of perfect metal square.

Keywords Tomography, Imaging, Defects, Conductivity

Industrial Application: Steel production