2D and 3D sampling schemes for fast multilevel field back-propagation algorithm

Fast source imaging method based on Rayleigh-Sommerfeld (RS) back-propagation accelerated by multilevel nonuniform grid algorithm (MLNG) is developed. 2D sampling schemes in spherical and oblate-spheroidal coordinates are compared to the full 3D spherical scheme in terms of efficiency and accuracy. The method is evaluated on the example of a parabolic reflector with a number of surface distortions. A good agreement between the results of 2D and 3D schemes is achieved. Accuracy of the proposed algorithms is studied by comparing the reconstructed source fields to those obtained via the direct RS integration.