EDDY CURRENT MAPPING INSIDE A PLANE CONDUCTOR WITH FLAWS

When a constant field probe with sinusoidal excitation is used to detect flaws inside a conductor, the lines of current must be uniform in a limited area under the influence of the constant excitation field. The existence of flaws inside the metallic material force the current to deviate from the uniform previous configuration. A magnetic field sensor may be used to measure one component of the magnetic field perturbation due to the eddy current anomalies.
In this paper a giant magneto-resistor sensor is used to measure the magnetic field perturbation. The measured field is used to infer about the current perturbation, and a final current density map is obtained. The inversion algorithms are based on a deconvolution process with regularization. The kernel is precisely the field of a single eddy as detected by the magnetic sensor.