Holography

Holography is the process or technique of making holograms, which are three-dimensional images. A hologram is produced by the interaction of two beams of laser light (light composed all of the same color, or wavelength), which have been split from a single beam by a mirror.

One beam, called the object beam, lights up the subject of the hologram. These light waves are reflected onto a photographic plate. The other beam, called a reference beam, is reflected directly onto the plate itself. The two beams come together to create, on the plate, an "interference pattern." After the plate is developed, a laser light is projected through this developed hologram at the same angle as the original reference beam, but from the opposite direction. The pattern scatters the light to create a projected, three-dimensional, ghostlike image of the original object