Electromagnetic testing and image reconstruction with flexible scanning tablets

An eddy current testing (ECT) and an electromagnetic acoustic testing (EMAT) employ electromagnetic methods to induce an eddy current and to detect flaws on or within a sample without directly contacting it. ECT produces Lissajous curves, and EMAT gives us a time series of signal data, both of which can be directly displayed on nondestructive testing (NDT) equipment screens. Since the interpretation of such output is difficult for untrained persons, images need to be properly reconstructed and visualized. This could be carried out by single-probe 2/3D scanners with imaging capabilities or with array probes, but such equipment is often too large or heavy for ordinary on-site use. In this study, we introduce a flexible scanning tablet for on-site NDT and imaging of detected flaws. The flexible scanning tablet consists of a thin film or a paper with a digitally encoded coordinate system, applicable to flat and curved surfaces, that enables probe positions to be tracked by a specialized optical reader. We also discuss how ECT and EMAT probe coordinates and measurement data could be simultaneously derived and used for further image reconstruction and visualization.