Maximum visibility under unitary transformations in two-pinhole interference for electromagnetic fields.

In terms of the spectral density tensors associated with the electric field vector, the maximum visibility one can obtain in a two-point interference arrangement by using local (i.e., position-dependent) unitary transformations applied at such points is determined. It is also shown that the maximum visibility can be expressed in terms of a number of well-known parameters describing the coherence and polarization features of the field.