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ptycho/utils/fresnel_tilt_propagation.m

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+function [OUT]=fresnel_propagation(IN,dxy,z,lambda)
+%FRESNEL_PROP Summary of this function goes here
+%   Detailed explanation goes here
+%Parameters:    dx,dy  -> the pixel pitch of the object
+%               z      -> the distance of the propagation 
+%               lambda -> the wave length 
+%               X,Y    -> meshgrid of coordinate 
+%               IN     -> input object
+
+[M,N]=size(IN);
+k=2*pi/lambda;
+
+%coodinate grid
+lx=linspace(-dxy*M/2,dxy*M/2,M);
+[x,y]=meshgrid(lx);
+
+% coordinate on the output plane
+fc=1/dxy;
+fu=lambda*z*fc;
+lu=ifftshift(ifftshift(linspace(-fu/2,fu/2,M),1),2);
+
+[u,v]=meshgrid(lu);
+
+
+if z>0      
+    pf=exp(1j*k*z)*exp(1j*k*(u.^2+v.^2)/2/z);
+    kern=IN.*exp(1j*k*(x.^2+y.^2)/2/z);
+    
+    kerntemp=fftshift(kern);
+    cgh=fft2(kerntemp);
+    OUT=fftshift(fftshift(cgh.*pf,1),2);
+else
+    z=abs(z);
+    pf = exp(1j*k*z)*exp(1j*k*(x.^2+y.^2)/2/z);
+    cgh = ifft2(ifftshift(IN)./exp(1j*k*(u.^2+v.^2)/2/z));
+    OUT = fftshift(cgh)./pf;      
+
+
+end
+