ABSTRACT
Objects with a vortex structure exist in a variety of areas of the material world: in the macrocosm, in the microcosm and in people's daily lives. Their structure and behaviour have not as yet been exhaustively studied and represent a vast field for research. Singular peculiarities in light fields can appear as they pass through randomly inhomogeneous and non-linear media. It is also possible to excite eddy fields in laser resonators and multimode optical fibres. The simplest elements of singular optics are the spiral phase plate and the spiral axicon. The nature of diffraction for the limited flat beam and the Gaussian beam varies in the Fresnel zone, but the distributions of the beams in the far-field are very similar. The chapter assumes the use of the singular optics elements for apodization of the transmission function of the lens. The paraxial scalar theory was used to consider different beams on the spiral phase plate.
