I've always thought that optical transforms were a great model for the determination of crystal structures using X-ray diffraction, and I've used the ICE (Institute for Chemical Education) kit for this exercise many times. Brian Hayes, a former editor of American Scientist, has a description with many very cool illustrations of his experiments with computer-generated analogs of the same phenomena that the ICE kit and a laser pointer or a little HeNe laser will let you do in a classroom. He provides the source code he used for generating the figures, but it is in a language (Scheme) with which I am not familiar. On the other hand, it shouldn't be too difficult to make them using any of several more familiar computer languages. I also recommend one of the references in this paper, Atlas of Optical Transforms, by G. Harburn, C. A. Taylor, and T. R. Welberry, Cornell University Press (Ithaca, New York) 1975. Sigma Xi provides much of the content of American Scientist online, but the link for this article has expired.