Generation of chain like beams.

Abstract

Wide application of the laser beams in science, technology and biomedicine demands the generation of the beams with desirable structure. In particular for optical trapping the beams with high transversal gradient of intensity distribution or doughnut like structures which carried out the orbital angular momentum are designed. In the recent study of the diffraction on the fractal Cantor zone plates [1-5] the possibility to generate the beams with capsule like structure (closed cylinder with the axis along the direction of beam propagation) for a certain distances has been discovered [5]. This peculiar form of the beam can be used for three dimensional particle trapping. Nevertheless the fractal zone plates are not unique gratings that generate this type of structures.