# Can I know the reconstruction of phase shift interferometry in Matlab

#### Leena Thomas

I want to know the reconstruction of phase shift interferometry by angular spectrum method in matlab

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#### berkeman

Mentor
Welcome to the PF.

What research and reading have you been doing so far on this? Can you post some links? What other work have you done in Matlab that may be of similar complexity?

I did a Google search on your thread title, and got lots of useful hits. Please show us what you have done so far, to help us try to give you some help. Sounds like an interesting project. Is this for school? Or your work in an industrial lab?

#### Leena Thomas

I go through some papers on which hologram image is produced by PSI. So I think of its reconstruction.

#### Leena Thomas

Code:
clear all; close all;

% parameter setup
M=256;
deltax=0.001; % pixel pitch 0.001 cm (10 um)
w=633*10^-8; % wavelength 633 nm
z=25; % 25 cm, propagation distance
delta=pi/2; % phase step (change it to show part b)
%Step 1: Simulation of propagation using the ASM
r=1:M;
c=1:M;
[C, R]=meshgrid(c, r);
A0=fftshift(ifft2(fftshift(I)));
deltaf=1/M/deltax;
p=exp(-2i*pi*z.*((1/w)^2-((R-M/2-1).*deltaf).^2-((C-M/2-1).*deltaf).^2).^0.5);
Az=A0.*p;
EO=fftshift(fft2(fftshift(Az)));
%Step 2: Interference at the hologram plane
AV=(min(min(abs(EO)))+max(max(abs(EO))));
% the amplitude of reference light
% Recording of Four phase-shifting holograms
I0=(EO+AV).*conj(EO+AV);
I1=(EO+AV*exp(-1j*delta)).*conj(EO+AV*exp(-1j*delta));
I2=(EO+AV*exp(-2j*delta)).*conj(EO+AV*exp(-2j*delta));
I3=(EO+AV*exp(-3j*delta)).*conj(EO+AV*exp(-3j*delta));
MAX=max(max([I0, I1, I2, I3]));
figure(1);
subplot(2,4,1);imshow(I);
title('Original object')
axis off
figure(1)
subplot(2,4,2)
imshow(I0/MAX);
axis off
title('hologram 1')
subplot(2,4,3)
imshow(I1/MAX);
axis off
title('hologram 2')
subplot(2,4,6)
imshow(I2/MAX);
axis off
title('hologram 3')

subplot(2,4,7)
imshow(I3/MAX);
axis off
title('hologram 4')
%Step 3: Reconstruction
CH=(I0-I2)-1j*(I1-I3); % the complex hologram (4-step PSH)
%A1=fftshift(ifft2(fftshift(CH)));
%Az1=A1.*conj(p);
%EI=fftshift(fft2(fftshift(Az1)));
%EI=(EI.*conj(EI));
%EI=EI/max(max(EI));
%figure(1);
%subplot(2,4,4)
%imshow(EI);
%title('Reconstructed image of 4-step PSH')
%axis off

U1 = ifft2(ifftshift(fftshift(fft2(CH)).*conj(p)));
Iangular = (1/(16*pi)).*(U1.*conj(U1));
EI=Iangular/max(max(Iangular));
figure(1);
subplot(2,4,4)
imshow(EI);
title('Reconstructed image of 4-step PSH')
axis off

s=PSNR(I,EI)

I did reconstruction of PSI but MSE found to be a high value............ is the reconstruction method correct? please help me.

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"Can I know the reconstruction of phase shift interferometry in Matlab"

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