Visualization of Acoustic Evanescent Waves by the Stroboscopic Photoelastic Method

Abstract

It is well known that evanescent waves are produced when an incident wave strikes an interface at an angle exceeding a critical angle and that they exhibit exponential decay within the refractive medium. Evanescent waves have been extensively studied and have attracted substantial attention for application in technology allowing expansion into the nano scale. However, the propagation of evanescent waves is not well understood visually. We have achieved acoustic evanescent waves produced when a propagating incident wave impinges on a water/glass interface at a post-critical angle, using the Fresnel method in the water and the photoelastic method in the glass.