Eddy current imaging of surface breaking defects by using monotonicity based methods

This paper is in the framework of the non-destructive evaluation of conductive materials by means of eddy current testing. In particular, we consider the imaging of surface breaking volumetric defects. In this case, it is possible to use relatively "high-frequencies" and, in the limit of skin-depth negligible with respect to the relevant geometrical sizes and negligible displacement current, the problem can be modeled as a magnetostatic one. The elliptic nature of magnetostatic allows proving a monotonicity property of the operator mapping the defects geometry into the measured quantity. This makes possible to use a recently proposed fast (non-iterative) imaging algorithm.