Matlab by GS algorithm for restoring the phase distortion of laguerre gaussian beams-CodePudding

Through the GS algorithm iterative calculation, the distortion of laguerre gaussian beam phase recovery, the question now is, iterative part of the code I think no problem, but still cannot restore the ideal phase, and finally calculate the beam pattern after the correction of purity is lower than even without calibration

 
For l=1: k 
F=abs (Ga). * (exp (I * I1x)); % the ideal of the amplitude and phase as the diffraction light field of input light field 
F=fft2(f); 
F=fftshift(F); 
GZF=abs (F); % get g after Fourier amplitude 
Gx=Angle (F); % after Fourier phase of g 
G2=abs (VGA). * (exp (I * gx)); % in the distortion of the vortex beam amplitude spectrum replace the ideal gaussian beam amplitude spectrum, new light field complex amplitude 
G2=ifftshift (g2); % diffraction inverse operation of the light field 
F2=ifft2 (g2); % diffraction inverse operation of the light field 
I1x=Angle (f2); % diffraction inverse operation to get the phase spectrum of 
Final=I1x; 
B=Final; % of phase distortion 
GSI=H - B; 
U3=abs (I2). * exp (I * GSI); 
End