Properties of the shadow cast by a half-screen when illuminated by a Gaussian beam

Optical components such as irises, knife edges, and baffles are employed for their blocking and shadowing properties. Optical fields in the form of Gaussian beams cannot be described by ordinary rays. Hence, the shadow cast by optical components when illuminated by a beam is not given by geometrical optics. Starting with an exact integral representation for the field when a Gaussian beam is shadowed by an edge, the locations of the shadow boundaries are found. The nature of the field in the vicinity of the shadow boundaries is investigated. It is found that for some parameter ranges, the field near the shadow boundary can be found from simple expressions, without the need of special connecting (transition) functions.