Using the coherence matrices derived in Part I of this investigation, a systematic study is made of structure of the far field, on the basis of several different theories. First the case of a completely polarized incident field is considered and the distribution of the energy density and the state of polarization are examined. Then the case of diffraction of an unpolarized field is studied, particular attention being paid to degree of polarization of the diffracted field. Analytical as wvell as some numerical results are presented. The predictions of the three theories are compared with each other and with those of the classical scalar theory of Huygens, Fresnel, and Kirchhoff.
B. KARCZEWSKI and E. WOLF, "Comparison of Three Theories of Electromagnetic Diffraction at an Aperture. Part II: The Far Field," J. Opt. Soc. Am. 56, 1214-1218 (1966)