New experiments on knife-edge diffraction

While the near-field effect from a knife edge has been well studied, the far-field effect has not been investigated yet. This paper presents an experimental study of both the Fresnel and Fraunhofer diffractions from a knife edge and reveals some puzzling features, which cannot be explained by the wave theory of light. By applying diffuse reflection to the infinitesimal structure of knife edge at nanometre scale, the paper can explain qualitatively the diffraction patterns observed in the experiments. It is suggested that manmade nanostructures may be used to study the knife-edge diffraction patterns quantitatively.