Evaluation of the limits of application for numerical diffraction methods based on basic optics concepts

The numerical propagation of an optical field from an aperture to infinity can be performed by the combined used of the angular spectrum and Fresnel-Fraunhofer transform numerical methods. There is a limit, computed by considering the correct sampling of the impulse response of the free space, which dictates the boundary of application of each method. In this work, the limits of application for these two numerical methods to compute the propagation of optical fields are evaluated. Angular spectrum and Fresnel-Fraunhofer transform diffraction methods are assessed as the reproduction of the phase forecasted by Babinet's principle is used as metric. This evaluation leads to the conclusion that the commonly utilized limit to split the range of application for the angular spectrum and Fresnel-Fraunhofer transform methods should be revisited. New limits in terms of the utilized number of pixels to sample a 2 pi-phase jump are proposed. (C) 2015 Elsevier GmbH. All rights reserved.