OPTICAL VORTICES PRODUCED WITH A NONSPIRAL PHASE PLATE

We present simple methods to produce optical vortices on the axis of b eam propagation with nonspiral phase plates. We show that a phase plat e that provides linear phase retardation on one half of a laser beam p roduces optical vortices, which is demonstrated experimentally by use of a thickness-varying glass platelet. We also demonstrate and explain that mixed dislocations of a bent edge dislocation transform into a p air of vortices with opposing topological charges. (C) 1997 Optical So ciety of America.