Patent ID: 11892285

Abstract:
A method of non-contact measurement of a thickness (d) of an object of an electrically conductive material by means of a Pulsed Eddy Current, PEC, system including a transmitter coil and a receiver coil. The method includes, after having turned off a current in the transmitter coil, at the receiver coil, measuring a voltage induced by the decaying magnetic field at a first time point, a second time point, and a third time point. The method also includes calculating a total magnetic flux which is generated by the eddy currents in the object at the first time point and picked up by the receiver coil, by comparing the measured flux at the first time point with a predetermined total flux picked up by the receiver coil when no object is present. The method also includes normalizing measured magnetic flux resulting from the eddy currents and picked up by the receiver coil, using the calculated total magnetic flux as a normalization factor such that the normalized eddy current flux is independent of a distance between the object and the transmitter and receiver coils. The method also including, based on the measurements at the first, second and third time points, determining the thickness and the resistivity of the object.