This paper presents an inversion problem algorithm
applied in eddy current inspection using a sinusoidal magnetic
field with fixed-amplitude, in a metallic plate sample with
machined crack defects. The uniform magnetic field is obtained
in a wide area around the probe due to the building technique of
the excitation coil. The magnetic sensor in use is a giant
magnetoresistance (GMR) with high sensibility. It measures the
amplitude and phase of the magnetic field originated from eddy
currents. A perturbation occurs in the measured magnetic field
in the proximity of a crack defect. The current density is then
determined around the crack defect through an inversion
problem algorithm. The applied method consists in determining
the transformation kernel and applying a Tikhonov
regularization algorithm. With this data it is possible to obtain
information about the defect geometrical characteristics.