Chernyshov A. Vector singularities in partially coherent light fields

A new class of vector singularities has been revealed and investigated, which are inherent in partially spatially coherent, inhomogeneously polarized light beams. For this purpose, the concept of the complex degree of polarization has been introduced with representation at the Stokes space bounded by the Poincare sphere that provides description of beams with arbitrary state and arbitrary degree of polarization. The introduced singularities, viz. U (unpolarized) contours and P (polarized) points at the transversal cross-section of a beam of partially coherent beam are the extrema of the complex degree of polarization. The sign principle governing singularities of this class has been established and proved experimentally, and the conditions of structural stability of such singularities are formulated. Valid experimental arrangements have been proposed for forming and analysis of such beams, as well as the means for computer processing of experimental data obtained through Stokes polarimetry of partially coherent beams. The conditions of appearing the mixed (coherent-to-incoherent) vector singularities have been realized, when C and L singularities of coherent singular optics co-exist and coincide in space with P and U singularities, respectively, whereas the weights of such singularities are determined by the degree of mutual coherence of orthogonally polarized components of the combined beam.