In the eddy current inspection of multi-layered structures in aircrafts, the detection of flaws in the subsurface layers is a significant challenge and requires very sensitive probles. These flaws are often present in the vicinity of edges of the structures and hence the inspection probe should ahso be capable of discriminating the defect signal from the edge signal. Edges in samples under inspection give rise to very large eddy current signals thereby masking any signals that the probe may detect from a flaw close to the edge. This is referred to as the edge effect. differential flux isgnal on inside and outside of the driver coil. A thin ferromagnetic shield around the probe coil is included to enhance the sensitivity of this probe.
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