The feasibility of noninterferometric methods to measure phase
distribution in a laser beam cross section for visualization of the
vortex dislocations of an optical speckle-field wave front is
analyzed. Peculiarities of the phase retrieved from the measured
intensity distribution (the phase problem in optics) and from the
wave-front slopes measured by a Hartmann sensor are discussed. A
concept of the vortex and the potential parts of the phase is
introduced. An analytic formula to retrieve the potential phase
from the measured intensity has been obtained. We show that the
considered means of measurements allow the positions of the dislocation
centers to be sensed and the spatial configuration of the intensity
zero lines to be reconstructed.
© 1998 Optical Society of America
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