Tech.Suramya.com: Holography

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Holography

A hologram is often described as a three-dimensional picture. A hologram contains information about the size, shape, brightness and contrast of the object being recorded. This information is stored in a very microscopic and complex pattern of interference. The interference pattern is made possible by the properties of light generated by a LASER. The light reflected by a three dimensional object forms a very complicated pattern that is also three-dimensional. In order to record the whole pattern, the light used must be highly directional and must be of one color. Such light is called coherent. Because the light from a laser is one color, and leaves the laser with one wave in perfect step with all others, it is perfect for making holograms.

A British/Hungarian scientist named Dennis Gabor developed the theory of holography in the late 1940's when he was working to improve the resolution of an electron microscope. He derived the term hologram from the Greek words holos, meaning "whole," and gramma, meaning "message."

In 1960's the pulsed-ruby laser was developed by Dr.T.H. Maimam of the Hughes Aircraft Corporation. This laser emits a very powerful burst of light that lasts only a few nanoseconds effectively freezing movement and making it possible to produce holograms of high-speed events, such as a bullet in flight, and of living subjects.

The first hologram of a person was made in 1967. In 1976 the Museum of Holography was founded to enable undrstanding and advancement of this new medium. In 1984 National Geographic became the first major publication to put a hologram on its cover.

A hologram is made by bathing a 3-dimensional object in the powerful beam of laser light. Light waves reflected from the object form a pattern which is recorded on special holographic plate. When this is developed and light is shone onto it, the original object is recreated as fully three-dimensional image. Unlike other 3-D "pictures", holograms provide what is called "parallax". Parallax allows the viewer to move back and forth, up and down, and see different perspectives -- as if the object were actually there.

Basic Setup for creating a Hologram

Holography has many varied uses in fields like art, science and technology. You may find holograms on certain product packaging at your local store. Several magazines have featured holograms on their covers. Holograms are found on credit cards, driver's licenses, and even clothing to help stop counterfeiting. It is possible to take flat medical images, such as a CAT scan and have the final image as a three-dimensional hologram. Computer-generated holograms allow engineers and designers to visually see their creations like never before.

Engineers also use holography to test for fractures and also for quality control during manufacturing. It is called holographic non-destructive testing. Holograms are used in many airplanes, both civilian and military. These holograms provide the pilot with critical information while looking through the cockpits window. It is called a heads-up display. Heads-up displays are now available in certain automobiles as well.

Artists use holography for artistic expression. Many artists feel that exploring the three-dimensional space and pure light that holography offers allows them to convey images and messages that were never before possible with "traditional" media.

Nowadays scientists are working on using holograms to store information. This is called holographic data storage. With HDS, you can store the entire contents of the Library of Congress in the area the size of a sugar cube.

Who knows soon we could have the capacity to generate holograms of ourselves so that we could be at two places at the same time. Now that opens up a lot of possibilities doesn't it?