DIFFRACTION

The deviation of an electromagnetic wavefront from the path predicted by geometric optics when the wavefront interacts with, i.e. , is restricted by, a physical object such as an opening ( aperture ) or an edge. ( 188 ) Note: Diffraction is usually most noticeable for openings of the order of a wavelength . However, diffraction may still be important for apertures many orders of magnitude larger than the wavelength.