DIFFRACTION OF PARTIALLY COHERENT BEAMS ON 3-DIMENSIONAL PERIODIC STRUCTURES AND THE ANGULAR SHIFTS OF THE DIFFRACTION MAXIMA

The scattering of electromagnetic fields of arbitrary state of coheren ce and polarization and of arbitrary spectrum by three-dimensional per iodical structures is described in the first-order Born approximation and under assumptions of statistical stationarity and quasihomogeneity of the fields. It is shown that, in general, the angular dependence o f the radiant intensity of scattered radiation is influenced and modif ied by the coherence properties of the incident radiation. The results are illustrated by examples that indicate that when x rays are scatte red by a crystal, shifts of diffraction maxima due to partial coherenc e of incident beam may appear, both in the Laue method and in the powd er method.