It is shown experimentally that by placing a flat screen with an axial hole
in a diffraction field formed by the first open Fresnel zone upon diffract
ion of a plane electromagnetic wave from a parallel screen with a hole of a
larger diameter, one can observe diffraction multifocal focusing of radiat
ion in the near-field zone of the first screen. The diffraction pattern in
the near-field zone of the first screen in focal planes represents circular
nonlocalised Fresnel bands with a bright narrow peak at the centre, whose
intensity is 6-10 greater than that of the incident wave.