A few months ago I came across an old piece of bulletproof glass I bought in high school when I was trying to make a camera shield for a thermite project. I had a little bit of free time, and so I was reminded of William Beatty’s famous method for making holograms, in which a virtual image can be created by literally scratching a pice of acrylic glass. I tried to make a simple star pattern, and the resulting video does not really do the effect justice:
A much better video comes from the author himself:
A detailed tutorial is available on Bill Beatty’s colorful website, amasci.com. Because the depth below the surface at which the virtual image appears scales with the radius of curvature of the arcs scratched into the glass, more sophisticated images can be generated by varying the radius of curvature in order to create images at multiple depths—allowing one to create a real 3D rendering rather than a 2D image that appears to sit below a surface.