Partially coherent sources with circular coherence: comment

In [Opt. Lett. 42, 1512 (2017)], the authors present a new class of non- uniformly correlated sources with circular coherence. They also describe a basic experimental setup for synthesizing this class of sources, which uses the Van Cittert-Zernike theorem. Here, we present an alternative way to analyze these sources and a different way to generate them.