You can actually use a laser, run it through a beam expander, pass it through a projector slide, run it through a lens, apply the filtering operations at the fo

You can actually use a laser, run it through a beam expander, pass it through a projector slide, run it through a lens, apply the filtering operations at the focal plane just like you would with a fourier transformed image, and get the expected result out. I thought this was just something cool you could do with lasers, but it seems that there is maybe some use for this: https://en.wikipedia.org/wiki/Optical_computing#Optical_Fourier_Co-processors https://en.wikipedia.org/wiki/Optical_computing#Optical_Four...