Generalized Van Cittert-Zernike Schell propagator: an efficient algorithm for simulating partially coherent light.

We present a wave propagation algorithm that models the diffraction of partially spatially coherent light and can be efficiently computed using a single forward propagation. The model uses the Van Cittert-Zernike theorem to find the complex coherence factor from a light source reaching the object plane, and it then uses the generalized Schell's theorem to compute the diffraction pattern produced at a given propagation distance, not limited to the far field. The numerical propagation is computed by a series of fast Fourier transforms, and it can be adapted to use any existing coherent propagator, giving it high flexibility with minimal additional computational cost. We report speed improvements up to two orders of magnitude and accuracy improvements up to three orders of magnitude over sample-based methods to model partially spatially coherent light in computer-generated holography (CGH) and digital holography (DH).