A numerical approximation of the Huygens-Fresnel integral - Simulations of a rough wetting problem

Computing numerical approximations of the Huygens-Fresnel principle in three dimensions is demanding in terms of time and hardware, but thanks to massive parallelization in GPGPU-enabled graphics cards these computations can be sped up considerably. Our newly developed software framework is capable of simulating many wave propagation-related problems. Although it was initially intended to generate laser speckle images for various real physical setups used to measure the surface roughness of sheet metal and/or the oil film thickness upon it, it turned out to also be suitable for larger setups and apertures. This paper gives a short overview of the underlying physical and mathematical concepts and elaborates on the strengths and weaknesses of the numerics. We describe the theoretical background of rough wetting and the core parts of the software. Further, we present several test cases using apertures and their known Fraunhofer diffraction patterns and objective speckle patterns generated for rough surfaces.