EXPANSION OF THE CROSS-SPECTRAL DENSITY-FUNCTION OF GENERAL FIELDS AND ITS APPLICATION TO BEAM CHARACTERIZATION

An expansion of the cross-spectral density function of partially coherent beams is given in terms of the Hermite-Gauss functions. The concepts of the characteristic matrix of a general field is introduced and a number of its properties are presented, including their propagation behaviour through ABCD optical systems. Also the relation between the above expansion and the first and second-order intensity moments of the beam is shown and its connection with the usual beam quality parameter is presented. Finally, the correspondence between coherence and quality is discussed.