BEAM COHERENCE-POLARIZATION MATRIX

We present an approach for describing the properties of a quasi-monoch romatic, beam-like field that is both partially polarized and partiall y coherent from the spatial standpoint. It is based on the use of a si ngle 2 x 2 matrix, called the beam coherence-polarization matrix, whos e elements have the form of mutual intensities. This approach, which c an be viewed as an approximate form of Wolf's general tensorial theory of coherence, appears to be very simple, yet it is able to cover sign ificant aspects of the beam behaviour that would not be accounted for by a scalar theory or by a local polarization matrix approach. A pecul iar interference law applying to mutual intensities is derived. We sho w through simple examples how this approach leads to distinguish field s that would appear identical in a scalar treatment or in a local pola rization matrix description. Hints for extensions are given.