par

ed fo It is demonstrated that the spectral degree of coherence of a partially coherent beam may possess isolated pairs of The field of singular optics [1], which has pri-marily been studied with fully coherent, mono-dictions have since been verified experimentally [4] and such spectral changes have been shown by Berry to be a characteristic feature of polychro-singularities of two-color vector fields and char-acterized the so-called Lissajous singularities Youngs interference experiment may possess pairs of points in the region of superposition at which the spectral degree of coherence of the field is equal to zero. It was further shown that these pairs of points can be associated with pairs of surfaces for which the spectral degree of coherence vanishes i