Modification of Fresnel Diffraction by a Straight Edge Object with Acoustically Coherence-controllable Illumination

Abstract

An attempt to modify a ringing fringe pattern of Fresnel diffraction is described. Fringe formation is heavily dependent on the illumination condition of partial coherence, controlled by a progressive acoustic wave. Periodic envelope modification results in a fringe pattern due to periodicity of the acoustic wave. The ringing is appreciably suppressed near the geometrical shadow edge of the object. Successive maxima and minima of the fringe pattern are reversed if the acoustic power crosses over a critical level.