Unambiguous coherence retrieval from intensity measurements

It is demonstrated that the members of different classes of two-dimensional fields that have the same intensity distributions everywhere in free space but different coherence properties can be identified by measuring the fields' intensities after passing the fields through an anamorphic optical system, such as a cylindrical lens. In this way the ambiguity in coherence determination from intensity measurements alone, present for the case of two-dimensional fields, is removed.