Well, the other day I was scanning the logs of what people had accessed off my site, and found that someone had apparently found my website while looking Thad Walker’s paper Holography without Photography. Walker wrote on how you could write a simple C program (a dubious example was included in the paper) and use it to compute an image which you could then print on a laser printer, and then when you shine a laser through it (in a specific way involving a lens or two, but nothing too fancy), you can get the original image out.
Well, actually two copies of the image, one reversed from the other. And a bright red spot in the middle.
In the post above, I said I should do it sometime.
So I did.
And here it is. You might not be able to tell, but the icon I was trying for was a brain. It actually looks better in real life than it does here, but the resolution is limited to about 60×60 pixels, so I probably should have tried a simpler image. Still, I was kind of pleased with the result, as useless as it is.
When I get the system all worked out and understand the math more, I’ll post a more elaborate HOWTO. Till then, try absorbing Walker’s paper.