Propagator.m

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% WAVEFRONT PROPAGATION BY ANGULAR SPECTRUM METHOD
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% Citation for this code/algorithm or any of its parts:
% Tatiana Latychevskaia and Hans-Werner Fink
% "Practical algorithms for simulation and reconstruction of digital in-line holograms",
% Appl. Optics 54, 2424 - 2434 (2015)
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% The code is written by Tatiana Latychevskaia, 2002
% The version of Matlab for this code is R2010b

function [p] = Propagator(N, lambda, area, z)

p = zeros(N,N);

for ii = 1:N
    for jj = 1:N
        alpha = lambda*(ii - N/2 -1)/area;
        beta = lambda*(jj - N/2 -1)/area;
        if ((alpha^2 + beta^2) <= 1)
        p(ii,jj) = exp(-2*pi*1i*z*sqrt(1 - alpha^2 - beta^2)/lambda);
        end
    end
end
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