Metal Surface Defect Detection Using Surface Plasmon Polaritons

This article presents a method for metal defect detection by using the surface plasmon polaritons (SPP). This is a type of transverse magnetic (TM) electromagnetic wave which can only exist on a metal-dielectric interface, which means that it is sensitive to the change of the shape of metal-dielectric surface. Scattered field from this deformation can help recreating the image of this metal-dielectric surface using angular spectrum propagation. The evaluation is carried out using finite-difference frequency-domain simulations.