Holography

Holography, technique for recording and reproducing 3-dimensional images by means of laser beams. The picture taken by the technique, the hologram, is a piece of photographic film that records not the scene itself but the unfocused pattern of light waves coming from the scene. A hologram is made by illuminating both the scene and the film with laser light, which has the important property of containing light of only 1 color (or wavelength). Light reflected from objects in the scene interferes with light from the direct, or reference, beam, producing a light-and-dark pattern of interference fringes. When light from a laser is passed through the developed hologram, the original pattern of light from the scene viewed is recreated in every respect. Thus the original scene will be visible in 3 dimensions, and the person viewing can look “behind” it by moving his or her head sideways. The method was invented in the 1940s by D. Gabor, who received the Nobel Prize in physics in 1971 for his work.