Defining And Understanding Holography Physics Essay

Defining And Understanding Holography Physics EssayHolography,methodofobtaining three-dimensional ruptureic images. These images are obtained with away a lens, so the method is withal called lensless photography. The records are called holographs (Greek holos, whole gram, message). The theoretical principles of holography were authentic by the British physicist Dennis Gabor in 1947. The prototypical actual issue of holograms took place in the early 1960s, when the laser became available. By the late 1980s the production of true-color holograms was possible, as well as holograms ranging from the microwave to the X-ray region of the spectrum. ultrasonic holograms were also being made, using sound waves.Holographyis one of the remarkable achievements of a modern science and technology. Holograms have unique property to restore the high-grade volumetrical image of real subjects. The war cry holography originated from the Greek words holos whole and grapho write, that means comp lete record of the image.Holography represents photographic process in a broad scent out of this word, essentially differs from a usual photo because there is a registration not onlyintensityin a photosensitive material, only if alsophaseof light waves, scattered by the object and carried the complete information about three-dimensional structure of the object. As the medium of mapping of the reality, hologram has unique property unlike usual photo, theholographic image so-and-so reproduce exactly three-dimensional copy of the original object. Such image with set of medical prognosiss, change with change of supervision, has amazing realness and often looks like the real object. Unlike photography or painting, holography can render an object with complete dimensional fidelity. A hologram can create e verything your eyes see size, shape, texture and relative position. However, if you try to touch a holographic image, all youll find is focused light. bill of holographyHolography i s known from 1947 when British (native of Hungary) scientist Dennis Gabor produced the theory of holography tour he was trying to improve the resolution of electron microscope .Gabor coined the term which we know today i.e. holography by the greek word holos, which means whole while gramma means message. Further development in the field was during the next period because light sources available at that date was not truly coherent .This problem was overcome in1960by Russian scientistsN. BassovandA. Prokhorovand American scientistCharles Townswith by the invention of the laser, whose pure, intense light was ideal for devising holograms. In that year the pulsed-ruby laser was developed by Dr.T.H. Maimam. This laser system(unlike the continuous wave laser normally used in holography) emits a very powerful burst of light that lasts only a a few(prenominal) nanoseconds (a billionth of a second). It effectively freezes movement and poses 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 in1967, paving the way for a specialized practise of holography pulsed holographic portraiture.In1962Emmett Leith and Juris Upatnieks of the University of Michigan recognized from their work in side- understanding radar that holography could be used as a 3-D visual medium. In 1962 they read Gabors paper and simply out of curiosity decided to duplicate Gabors technique using the laser and anoff-axis techniqueborrowed from their work in the development of side-reading radar. The result was the first laser transmissionhologram of 3-D objects (a toy train and bird). These transmission holograms produced images with clarity and realistic depth but required laser light to visual modality the holographic image.Their pioneering work led to standardization of the equipment used to make holograms. Today, thousands of laboratories and studios possess the necessary equipment a continuous wave l aser, optical devices (lens, mirrors and beam splitters) for directing laser light, a film holder and an isolation table on which exposures are made. Stability is absolutely essential because movement as small as a quarter wave- length of light during exposures of a few minutes or even seconds can completely spoil a hologram. The basic off-axis technique that Leith and Upatnieks developed is still the staple of holographic methodology.Also in1962Dr.Yuri N. Denisyukfrom Russia combined holography with 1908 Nobel Laureate Gabriel Lippmanns work in natural color photography.Denisyuks approachproduced a white-light reflection hologram which, for the first time, could be viewed in light from an ordinary incandescent light bulb.Another major advance in display holography occurred in1968when Dr.Stephen A. Bentoninvented white-light transmission holography while researching holographic television at Polaroid Research Laboratories. This type of hologram can be viewed in ordinary white light creating a rainbow image from the seven colors which make up white light. The depth and brilliance of the image and its rainbow spectrum soon attracted artists who adapted this technique to their work and brought holography further into public awareness.Bentons invention is peculiarly significant because it made possible mass production of holograms using an embossing technique. These holograms are printed by stamping the interference pattern onto plastic. The resulting hologram can be duplicated millions of timesfor a few cents apiece. Consequently, embossed holograms are now being used by the publishing, advertising, and banking industries.In1972Lloyd Crossdeveloped the integral hologram by combining white-light transmission holography with unoriginal cinematography to produce moving 3-dimensional images. Sequential frames of 2-D motion-picture footage of a rotating subject are recorded on holographic film. When viewed, the composite images are synthesized by the human brainpo wer as a 3-D image.In 70s Victor Komar and his colleagues at the All-Union Cinema and Photographic Research Institute (NIFKI) in Russia, developed a prototype for a projected holographic movie. Images were recorded with a pulsed holographic camera. The developed film was projected onto a holographic screen that focused the dimensional image out to several points in the audience.Holographic artists have greatly increased their technical knowledge of the discipline and now contribute to the technology as well as the creative process. The art form has become international, with major exhibitions being held throughout the world.The commonly and widely used way of imaging of the reality is the photography. A photograph is basically the recording of the differing intensities of the light reflected by the objectand imaged by a lens. However, information about dimensions of the object contained not only in amplitude (intensity), but also in a phase of light waves.A great difference between holography and photography is the information recorded. This difference is why photographs are twain dimensional (2-D) images while holograms are three dimensional (3-D) images. Photographs contain only one view point of an object. Our eyes need a minimum of dickens view points in order to see depth. Vision using two viewpoints of an object is called stereoscopic vision. Each eye receives a slightly contrasting view point of an object, our brain combines the two and we perceive depth. We can fool our eyes into seeing photographs in three dimensions by taking two slightly different views of an object and allowing each eye to see only one image, the right image for the right eye and the left image for the left eye. We can do this with a stereoscope (for pictures) or with polarized glasses (for movies). The shortcoming of stereoscopic images is that when we move our head from side to side or up and down, we still only see the kindred two view points, whereas we should be seeing con tinuously changing viewpoints of the object. The image therefore doesnt quite appear to be three dimensional. In order to make a record of a three dimensional object we need to record this continuous set of viewpoints of the object.Estimating sizes of the objects and considering shapeand direction of shadows from these objects, we can create in our mind general representation about volumetric properties of the scene, represented in a photo. But, if sizes of the objects are identical and there are no shadows, volumetric bailiwick of the photographed scene is completely lost. For example, we can not define in the photo of snowflakes on a dark background, which of them is closer, and which of them is farther.Holography is the only visual recording medium that can record our three-dimensional world on a two-dimensional recording medium and playback the original object or scene to the unaided eyes as a three dimensional image. The image demonstrates complete parallax and depth-of-field and floats in space either behind, in front of, or straddling the recording medium.