Generating a couple of rotating nondiffracting beams using a binary-phase DOE

A binary phase diffractive optical element (DOE) is utilized to generate a couple of identical oppositely rotating (in a clockwise and counterclockwis e direction) nondiffracting light beams. The diffraction-free character of beam propagation is conserved up to a certain distance depending on the ape rture radius and on local characteristics of the DOE. Either of the beams i s described by a linear combination of Bessel functions of the first kind a nd of different orders and scale, multiplied by relevant angular harmonics. Theory and experiment an shown to be in good agreement.