FRAUNHOFER-DIFFRACTION PATTERN BY A SLIT APERTURE BETWEEN A KNIFE EDGE AND A METAL CYLINDER

The Fraunhofer diffraction pattern of an aperture formed between a kni fe edge and a smooth surface of a turned metal cylinder or half cylind er is different from the diffraction pattern of an ideal slit aperture . The diffraction pattern is simulated by adding the light reflected b y the cylinder surface to the pattern formed by a slit, and is measure d using a cylinder that has been partly cut away so that it can repres ent either a full or half cylinder. The theoretical and measured patte rns agree well with each other.