Marcel Leutenegger, Matthias Geissbuehler, Iwan Marki et al. We present a method for fast calculation of the electromagnetic field near the focus of an objective with a high numerical aperture (NA). Instead of direct integration, the vectorial Debye diffraction integral is evaluated with the fast Fourier transform for calculating the electromagnetic field in ... [Proc. SPIE Int. Soc. Opt. Eng. 6861, 68610R (2008)] published Tue Feb 12, 2008.