LAUSR

We report a form of double edge-diffraction (DED) for the first time, in which successive diffractive effects between two opaque objects leads to a virtual shadow of one object that protrudes from the shadow of the other. Analogous to classic edge and slit diffractions, the method to observe DED is simple, yet its effect is intriguingly different. Existing sensing techniques cannot measure the distance of highly reflective or absorptive opaque objects. To address this problem in certain scenarios, we propose a new technique based on DED that is the first to work for all opaque objects with well-defined edges.