I am comparing diffraction pattern images and their discrete Fourier transform (DFT). I know that since Fraunhofer diffraction is essentially a Fourier transform, the DFT of the resulting pattern gives me the intensity profile of the wave on the aperture. Well, the DFT does give me the aperture shape, but only the corners! Why is that?
This is the diffraction pattern caused by a green laser passing through an hexagonal aperture.
This is the DFT of the hexagonal aperture.