DIFFRACTION OF FOCUS WAVE MODES AT A PERFECTLY CONDUCTING SCREEN

We discuss the diffraction of scalar focus wave modes normally inciden t on the edge of a perfectly conducting half-plane S. The focus wave m odes are Gaussian-like beams with parameters depending on space-time. In the region of the beam where the profile is nearly Gaussian (the an alogue of the optical region for Gaussian beams) we get the total fiel d nu made of the incident, reflected and diffracted fields as a soluti on of the wave equation, continuous outside S and satisfying on S the boundary condition of either (nu)(s) = 0 or (delta(n) nu)(s) = 0, wher e delta(n) denotes the normal derivative. We also discuss the conditio ns making the diffraction possible and the generalization to electroma gnetic focus wave modes.