HOW PHASE AND AMPLITUDE ABERRATIONS DESTABILIZE THE PHASE SINGULARITIES IN THE FOCAL FIELD OF A LENS

The output field of a uniformly illuminated lens contains points of ze ro intensity on the optical axis and zero-intensity Airy rings in the focal plane, as formed by diffraction. These intensity zeros have been recognized as phase singularities or wave dislocations. Recently it w as shown that, under the influence of a perturbation, the axial singul arities may transform into rings or disappear and that the Airy rings may split into triplets. Starting from optical diffraction theory, we identify the physical perturbations that can induce such topological t ransformations. The basic perturbations are phase and amplitude aberra tions of the wave front that is incident on the lens; we show that the ir different natures have consequences for the possible dislocation re actions. (C) 1998 Optical Society of America. [S0740-3232(98)00811-4]. OCIS codes: 050.1220, 050.1940, 050.1960, 080.1510.