Phase singularities in beams

Beams of electromagnetic radiation with phase singularities can transport a ngular momentum and exert torques on objects. In this paper we discuss the generation of such beams and present a simple analysis of the phenomenon. T hese beams and their effects have been studied at optical and at millimeter wavelengths. We describe a particularly efficient way of generating these beams at millimeter wavelengths employing a specially configured blazed gra ting. (C) 1999 American Association of Physics Teachers.