I tried to study the diffraction pattern of the following zigzag grating by Matlab(FFT of this image)..
And the result showed like this(please ignore the scale bar in this img)
I think the program of FFT by Matlab is correct.. I am just wondering why, in the FFT, the midpoint(0,0) did not show the strongest intensity..Because I did some calculation by a simple model of zigzag(two lines), the midpoint always shows the strongest brightness..
Any suggestions are welcomed.