Storing Data in a Hologram

The traditional way of taking a three-dimensional photograph, or hologram, involves splitting a laser beam in two, reflecting one half (known as the object beam) off the thing that is to be holographed, and then recombining it with the other half (known as the reference beam) and exposing a photographic film to the result.

The process of recombination produces an interference pattern that is recorded on the film, and when this pattern is viewed in suitable lighting, an image that looks three-dimensional becomes visible to the eye.