This secondary field is dependent on the conductivity of the sample and is indirectly detected by the sensor coils. The primary field inductively couples with the sample object, generating a secondary opposing field B (Lenz’s Law) due to the eddy currents induced in the sample. The sensor-coil array and the sample object are placed in-between the Helmholtz coils. In our instrument, an alter- nating current is passed through a Helmholtz coil assembly, providing a near-to-uniform sinusoidal driving field. MIT principles rely on the establishment of eddy currents in a conductive object, and the detection of the magnetic field generated by these currents. We further discuss the potential for extending the system to a full 3-D imaging system, based on results of a disk-lift-off investigation.
In this paper, we report on an automated MIT system specifically designed to image metallic objects. Although much research has been undertaken in the biomedical MIT, the technique has not been well developed for imaging of metallic objects.
The term MIT is synonymous with electromagnetic induction tomography.
I NTRODUCTION M AGNETIC noncontact and induction nondestructive tomography electromagnetic (MIT) – imaging is a technique that has potential applications in security, industry, medicine, and geophysics.
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