Three theories of electromagnetic diffraction at an aperture in a screen, associated with the names of Kottler, Luneburg, Severin, and Vasseur, are reviewed and on the basis of these theories the coherence matrices relating to the far field are derived. These matrices will be used in Part II of this investigation to analyze systematically the structure of the far field as predicted by these theories.
B. KARCZEWSKI and E. WOLF, "Comparison of Three Theories of Electromagnetic Diffraction at an Aperture. Part I: Coherence Matrices," J. Opt. Soc. Am. 56, 1207-1210 (1966)