Hologram is a pattern, usually made on photographic film, which can produce a three dimensional image of a scene. This holographic image is so lifelike that it appears to be a real scene viewed through a window. The viewer can see around objects in the foreground by moving his/her head, just as he/she looks around real objects. If part of the hologram is covered, the complete scene can still be seen in the remaining part as if part of the window were covered. Holograms are produced by illuminating the scene with light from a device called a laser. The holographic image is then created by shining a similar beam of light on the hologram. The hologram changes this light to reconstruct the light patterns which came from the original scene. Holograms were invented in 1947 by Hungarian scientist Dennis Gabor, but they were ignored for years. Gabor's theory about light waves was ahead of its time. The lasers needed to produce clean waves and thus clean 3-D images weren't invented until 1960. Gabor coined the name for his photographic technique from holos and gramma, Greek for "the whole message. " But for more than a decade, Gabor had only half the words. Gabor's contribution to science was recognized at last in 1971 with a Nobel Prize.. A perfect holographic portrait of the late scientist looking up from his desk with a smile could go on fooling viewers into saying hello forever. When it comes to looking at the future uses of holography, pictures are anything but the whole picture. Here are just a couple of the more unusual possibilities. Consider this: you're in a windowless room in the middle of an office tower, but you're reading by the light of the noonday sun! How can this be? A new invention that incorporates holograms into widow glazings makes it possible. Holograms can bend light to create complex 3 D images, but they can also simply redirect light rays. The window glaze holograms could focus sunlight coming through a window into a narrow beam, funnel it into an air duct with reflective walls above the ceiling and send it down the hall to your windowless cubbyhole. That could cut lighting costs and conserve energy. The holograms could even guide sunlight into the gloomy gaps between city skyscrapers and since they can bend light of different colors in different directions, they could be used to filter out the hot infrared light rays that stream through your car windows to bake you on summer days. Or, how about holding an entire library in the palm of your hand? Holography makes it theoretically possible. Words or pictures could be translated into a code of alternating light and dark spots and stored in an unbelievably tiny space. That's because light waves are very, very skinny. About 1000 lightwaves can be placed side by side across the width of the period at the end of this sentence. One calculation holds that by using holograms, the U. S. Library of
could be stored in the space of a sugar cube. For now, holographic data storage remains little more than a fascinating idea because the materials needed to do the job haven't been invented yet. But it's clear that holograms, which author Isaac Asimov called "the greatest advance in imaging since the eye" will continue to make waves in the world of science.