Eddy-current testing (ECT) has a large contribution to the maintenance of apparatus with a high reliability both in the past and the future. The needle type magnetic probe with the giant magneto-resistance sensor made it possible to inspect minute defects in narrow spaces (groove and hole). Moreover, the high resolution and sensitivity of the detection methodology could observe the ECT signal image inside of hole and groove. In this paper, we discuss the 2-dimensional signal recognition of magnetic fields and distinguish the relationship and discrepancy between a shape of notch inside of narrow hole and a signal image by both experimental and calculated results.
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