Holograms A fully three dimensional picture floating in space has captured the imagination of science fiction writers for many years. Twenty years ago it was almost an unrealisable dream, but in these past 25 years the knowledge and technology associated with holography has increased in leaps and bounds. Yet strangely enough the concept of holography goes back to 1948, when Dennis Gabor, an engineer physicist, proved that three dimensional photographs could be produced apparently by the simple use of a light sensitive (photographic) plate. Twenty-three years later his discovery won him a Nobel Prize in Physics. Gabor was unable to progress his invention very much further owing to the absence of both a sufficiently strong source of light and of a suitable high quality emulsion for his light sensitive plates. He produced "Interferograms", albeit only millimetres in size, by shining a mercury vapour lamp through a pinhole of one thousandth of an inch, which demonstrated that his theory worked but aroused little interes in the invention. As in the pioneer days of photography almost a hundred years earlier, sceptics were eager to brand Gabor´s holography as an invention without a future. It takes a long time before a scientificially established principle or new invention is accepted and even more before it becomes taken for granted - the electric lightbulb, the telephone, the wireless, the television, the computer, landing on the moon - it is interesting however, that many inventions finally discovered by scientist have been visualized by writers and artists, in some cases, centuries before. In the fifteenth century Leonardo da Vinci made working drawings of an aeroplane and a submarine. In the last century Jules Verne wrote appear that most science fiction eventually can become fact and whatever people can imagine can become a reality. The facts of light 1564-1642 Galileo attempted to measure the velocity of light but concluded that its speed was infinite. 1672 Sir Isaac Newton succeded in splitting white light into the various colours of the spectrum with a prism. 1676 The Danish astronomer Ole Reomer deduced that light did have a measurable velocity by comparing the observed and calculated times of the eclipses on the moon of Jupiter. Dr. Thomas Young ( 1773 - 1829) established that light travels in a wave motion not unlike waves in the sea. 1882 The speed of light was established to be 299,778 kilometres per second. ( This has been revised to 299,792 kilometres per second or 186,282 * 397 miles per second) . 1913 Neils Bohr discovered that electrons could be raised to a higher energy level by exposure to outside energy sources. 1958 Charles H. Townes and Arthur L. Schawlow published a paper called 'inra-red and Optical Masers" proposing that atoms of a metallic vapour such as sodium or potassium could be pumped to excited states and then stimulated to emit coherent light radiation. Maser stands for Microwave Amplification Stimulated Emission of Radiation. They also established the basic design for a laser. 1960 The first Laser was built at the Hughes Aircraft Company Electronics Research Laboratories and Theodore H. Maiman achieved laser action there. Laser is an acronym for Light Amplification by the Stimulated Emission of Radiation. Holography - It's Application Holography is now an established part of our lives. It is used in Industry to detect faults, for example, in nuclear power generators, machine parts and car tyres. The precise measurements made possible by holography opened up an entire new area in Medical research and develpment from body scans to locate tumours - to the improved design or artificial hip joints. Holographic film provides a compact 3D filing system. in Dentistry it replaces the enormous storage area required to keep millions of dental moulds which must be kept for up to 12 years! In Art Restoration and Conservation holograms can record the damaging effect of damp on artifacts, making it possible to identify hidden damage and predict the possibility of further damage. Holographic Optical Elements (HOES) are the basis for holographic retrieval systems as used with the supermarket laser scanner. The British Telecom Phonecard and holographically coded credit and cheque cards which are virtually impossible to forge. In advertising the embossed hologram, mass produced at last cost, is used for example on record sleeves, key fobs and badges. Holography captures an ethereal beauty which cannot be achieved in any other medium. It produces strong visual statements and as a creative medium, holography has already made an important contribution to the visual arts and to the manner in which we see and interpret our surroundings.