Analytic expressions and approximations for the on-axis, aberration-free Rayleigh and Debye integral in the case of focusing fields on a circular apertureR. M. Aarts, J. J. M. Braat, P. Dirksen, S. van Haver, C. van Heesch and A. J. E. M. JanssenJ. Eur. Opt. Soc.-Rapid Publ., 3 (2008) 08039DOI: https://doi.org/10.2971/jeos.2008.08039
