initial commit

ptycho/utils/generate_probe.m

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+function [probe] = generate_probe(N, lambda, dx, Ls, setup)
+%UNTITLED Summary of this function goes here
+%   Detailed explanation goes here
+%Parameters:    N      -> number of pixels
+%               lambda -> the wave length 
+%               dx     -> pixel size (in sample plane)
+%               Ls     -> distance from focal plane to sample
+
+    %Fresnel Zone Plate
+    switch setup
+        case "velo"
+            Rn=90e-6; 
+            dRn=50e-9;
+        case "barry"
+            Rn=80e-6; 
+            dRn=70e-9;  
+        case "barry2"
+            Rn=70e-6;
+            dRn=160e-9;
+        otherwise
+            Rn=90e-6;
+            dRn=50e-9;
+    end
+    
+    fl=2*Rn*dRn/lambda;%focal length corresponding to central wavelength
+    D_FZP=180e-6;%dimeter of the FZP
+    D_H=60e-6;%central beamstop
+
+    %pixel size on FZP plane
+    dx_fzp=lambda*fl/N/dx;
+    %Coordinate on FZP plane
+    lx_fzp=linspace(-dx_fzp*N/2,dx_fzp*N/2,N);
+    [x_fzp,y_fzp]=meshgrid(lx_fzp);
+    %Transmission function of the FZP
+    T=exp(-1j*2*pi/lambda*(x_fzp.^2+y_fzp.^2)/2/fl); 
+    C=double(sqrt(x_fzp.^2+y_fzp.^2)<=(D_FZP/2));% Cercular function of FZP
+    H=double(sqrt(x_fzp.^2+y_fzp.^2)>=(D_H/2));%cental block
+
+    %probe on sample plane
+    probe=fresnel_propagation(C.*T.*H,dx_fzp,(fl+Ls),lambda);
+    %figure(1);imagesc(abs(probe));axis image
+    %figure(2);imagesc(angle(probe));axis image
+end