PARTIALLY COHERENT FIELDS, THE TRANSPORT-OF-INTENSITY EQUATION, AND PHASE UNIQUENESS

Recent papers have shown that there are different coherent and partial ly coherent fields that may have identical intensity distributions thr oughout space. On the other hand, the well-known transport-of-intensit y equation allows the phase of a coherent field to be recovered from i ntensity measurements, and the solution is widely held to be unique. A discussion is given on the recovery of the structure of both coherent and partially coherent fields from intensity measurements, and we rec oncile the uniqueness question by showing that the transport-of-intens ity equation has a unique solution for the phase only if the intensity distribution has no zeros.