Abstract

Optical vortices or phase singularities in optical fields have been known for a long time, and their basic properties have been studied extensively since the seminal work by Nye and Berry in the early 1970s. Recently, phase singularities have come to attract new attentions for different reasons in the fields of applications such as optical metrology and photon manipulation. Because of their orbital photon angular momentum, optical vortices have proved themselves a useful means for optical trapping and manipulation of atoms and micro particles. On the contrary, phase singularities have been regarded as a nuisance by researchers in optical interferometry and profilometry, because the phase singularities hinder unique phase unwrapping of the measured phase values, which are usually wrapped into the range [−π, π). Therefore, main efforts in optical metrology have been concentrated on how to get rid of the effect of phase singularities. A typical example is the phase unwrapping algorithm that directly kills out all phase singularities by superposing vortex fields with the phase singularities of opposite sign [1]. A question then naturally arises "Can phase singularities also prove themselves to be useful in optical metrology?"

© 2009 IEEE