Vector-mode analysis of symmetric two-point sources

Vector modes and eigenvalues are evaluated for a partially coherent source when only a pair of points is of interest, as in the case of the radiation emerging from the pinholes of a Young interferometer fed by an electromagnetic beam. Analytical results are presented, paying particular attention to those cases when the fields at the two points cannot be distinguished from one another on the basis of their second-order correlation properties. It is shown that the superposition scheme provided by the vectorial modal theory of coherence allows a simple interpretation of the interference pattern and an intuitive understanding of its coherence–polarization features to be given. Examples are given for the case of electromagnetic Gaussian Schell-model sources.