Comparison of the FRISP methode for the simulations based on Rayleigh-Sommerfeld diffraction followed by step-wise propagation and FDTD-simulations based on [12] (©2018 The Japan Society of Applied Physics). a) to d) results of FDTD-simulations, e) to h) results of the FRISP method. Refractive index n = 1.3 for (a) and (e), n = 1.5 for (b) and (f), n = 1.65 for (c) and (g) and n = 1.9 for (d) and (f) of a microsphere with a diameter of 10 μm.