function [Ep,deltaxi] = Fresnelprog1D_TFD_unique (En,deltax,lambda,z)

% Calcul de la propagation de Fresnel selon l'algorithme Huygens-Fresnel /
% TFD unique

N=length(En);
p=[(0:(N/2)-1) (-N/2:-1)];
Ep=deltax*...
    exp(1i*2*pi/lambda*z)/sqrt(1i*lambda*z)*...
    exp(1i*pi*lambda*z*p.^2/(N^2*deltax^2)).*...
    fft(En.*exp(1i*pi*(p*deltax).^2/(lambda*z)));

deltaxi=lambda*z/((N-1)*deltax);