“…The iterative procedure of single beam multiple intensity reconstruction (SBMIR) is based on sequential propagation of the field estimate v ( x , y , z ) between planes, where the measurement of intensities was registered preliminarily. [
61–63 ] The calculation of wavefront propagation between data acquisition planes in the Fresnel diffraction zone is carried out using the angular spectrum method. In a discrete the representation, the equation for calculating the field through representation of an angular spectrum of plane waves is described as follows:
where u 0 ( x ′, y ′) is the complex field distribution in the initial plane; Δ z is the distance of propagation;
and
denote fast forward and inverse Fourier transform operators.…”