HOLOGRAMS

Holograms are three-dimensional images that are created by recording the interference pattern of two or more beams of light. To create a hologram, a laser beam is split into two parts: the object beam and the reference beam. The object beam is directed at the object, and the light that is scattered from the object is recorded on a photographic plate. The reference beam is directed at the same photographic plate, and the two beams interfere with each other to create an interference pattern. When the photographic plate is illuminated with a laser beam, the interference pattern diffracts the light, creating a three-dimensional image of the object. Holograms can be found on most driver’s licenses, ID cards and credit cards. However, these holograms are not very impressive. They usually just look like sparkly pictures or smears of color. Large-scale holograms, illuminated with lasers or displayed in a darkened room with carefully directed lighting, are incredible. They’re two-dimensional surfaces that show absolutely precise, three-dimensional images of real objects.