Detection of rectangular tin inclusion in copper using laser-based self-referencing thermoelectric technique

This paper presents a laser-based self-referencing thermoelectric technique, like other thermoelectric techniques, which is completely insensitive to spurious geometric effects. The main advantage of this new thermoelectric technique is its sole sensitivity to intrinsic subtle material properties within a shallow layer close to surface, and therefore, this laser-based self-referencing thermoelectric technique can be exploited for NDE issues requiring limited depth material characterization. The successful detection of surface-breaking rectangular tin inclusions in copper has demonstrated that the laser-based self-referencing thermoelectric method has certain penetration depth. In addition, experimental results are shown to be in very good qualitative agreement with the prediction of a simple model developed to understand the relation between the measured and generated thermoelectric voltage. These results clearly demonstrate this laser-based self-referencing technique is a true near surface technique.