Holograms are the fringes of light recorded on a plate of extremely high-resolution film when light from a laser interferes with itself after reflecting off an object. This effect can also be simulated computationally by tracing light and it's diffraction around obstacles onto points on a simulated holographic plate. That is exactly what MedCosm CGHMaker does. It's written in Java and should work on any computer that has a working Java installation. After it computes the fringes, they can be displayed, saved as a gif, and printed out. After that, I photograph them onto Pan-F+ film to increase the density of the fringes by a factor of 10. After developing the roll, firing a laser through the plane of the film projects an image of whatever was rendered.

The size of the image that needs to be rendered is determined by what the destination medium is. If you're just going to laserjet it onto a transparency, 600x600 or 900x900 will do. If you plan to record it onto film, you'll need extremely slow black-and-white film and should start at 2400 pixels and go up from there. Trying to render such a large image will not work if you try to do it all at once; The memory consumption will make your computer implode. You'll have to render it in blocks (i.e. 7 600x3000 vertical strips) and then stitch them together. If you can get ahold of other computers, use them to render parts of the image.

Here are some of the holograms I've created and rendered:

My newest toy is creating holograms. These are easy to do conecptually, but in practice it can be a pit of a pain: You will need MedCosm CGHMaker to render them, a laser printer to move the generated images into meatspace, and finally Pan-F+ film to record them at 4000 instead of 600 DPI. Oh, and a laser to view them. But you've all got frickin' lasers sitting around the house, right?