In my course on Microphotonics there is a brief mention of a coherent optical processor system. My problem is I don't exactly know what it's for. Basically, what is said that a transparent input image (like a photograph) is lighted monochromatically and then focussed by a lens to a spot with another transparent layer with a given transmission function. If the light transmitted through this spot is again refocussed, the convolution of these two transmission function will be given. (At least, I think, maybe there's a phase factor I'm missing?) Anyway, at this point, the intensity can be given as: I(x3,y3) = K* abs[ (g*h)(x3,y3) ]^2 where (g*h)(x3,y3) = int(int( g(eps,eta) h(x3-eps,y3-eta), eps=-inf..inf),eta=-inf..inf) So So I think that this thing can be used to 'clean' an image up, by making h a filter function. However, I've been reading some on the net, and it appears that such a processor can also be used to reconstruct an image. How is that possible? 2. Also, I've read that nowadays, there are other and better techniques for stuff like this, and that one can even use incoherent light. Can anybody tell me something about that?