Simulation of partially coherent imagery in the space and frequency domains and by modal expansion

Three methods of digital simulation of partially coherent imagery are presented and compared. The first method is a direct discretization of imaging equations. In the second, the computations are performed in the Fourier domain. The third method is based on a modal expansion of the imaging as an incoherent sum of a number of coherent modes; this allows full utilization of FFT algorithms. It is shown that when the imaging is of narrow point spread function, the modal expansion method is very efficient, especially for relatively high coherence. Examples of 1-D and 2-D images are shown.