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On Hologaphy and a Way to Make Holograms

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On Hologaphy and a Way to Make Holograms I - ON HOLOG}iAPHY AND A WAY TO I'{AKE HOLOGRAMS by J. Pethiek Cover drawing by Peg Bennett, based on a seulpture by J. Pethi.ck &n #ltrvly rt"{ A BELLTOT/,JER B00K t. A *}ry *o 4o*" flohg;*r: ' 0 Belltower Enterpri-ses, 1971 Sherm 1z ON a Tube-mounted optlcar components inserted into washed HOLOGRAPHY silica sand provide a highfy stable a"A ff"xiUie AND system for rnaking holograms, The plywood. box eontaining the sand is rfloatedr on an inflated WAY TO MAKE HOLOGiiAIVIS inner tube for further vibration eontrol. by J. Pethick A Belltower Book Courtlry EdifiE t @ published in cooperation with the Umbra Foundation t\ BELLTOW.UR ENTJIRPRIS.!,S 2358 Lakeshore Rd. E. Burlington, Ontario, Canada I ,l tu-.-* CONCI;RNING HOI,OGRAPHY Holography is j_n Denis Gabor, nho eoneeived the idea of holography, its infancy. This means that nev nade information i_s continually tecoming first holograms wi-th a complicated whi-te light available, and source at the Imperial London, England, huge junps in overcoming its technical limit"iio.r, Institute in are being nade in short periocis in 1948. Because of the impractj-cability of the light of ti_me. source, little more xras done untj-I after the j-nvention There is littl-e in th-is booklet on pulsed of the laser in l-950. The laser was to supply the holography, ideal light source holography. whieh seems to be a much ress restrr,ilil-ray tI rork. for continued research in But at present it involves a great deal of Lxpense. The sand-based system describ-d her., originaiiy Finmett Leith and Juris Upatnieks, working at the developed and implemented at Editiori University of Michi-gan, obtained remarkable results tr,"] in Ann using a laser to nake holograms 1964. Their results Arbor, has been proven to be an i-nexpensive in and efficient-lrlichigan, approach to holography. ' established holography as a medi-um of the future, enabling the storage or rcapturing, of three-dj-men- sional visual information two-dimensj-onal plane. I would J.ike to thank and. acknowledge the help of on a Lloyd Cross, Allyn Lite, Don Broadbent and nany others In a short time other laboratories were nraking holo- who contributed towards the infornration and exieri-ence grams, but holography did not seem to serve the highly that have niade this bookr-et possibre. speciar thanks Lo l,largaret technological industries rvith enough economically Southcomb and DaryI Sharp tor typing and editing the material_. feasible applications. Consequently, it was often treated merely as a laboratory whimsi-cality. The ' search for applicati-ons conLinued, while a few people, The way to t,echnical and artistie acivance holography in including some of the scientists working 1n the l-ies in the sharing of resources and information. rt fleld, is hoped that the non-profj_t Udra Foundation, were learni-ng more about the potential and ]imitations San of holography simply as a visual meciium. Francisco, wirr be able to assist many of those inter- ested i-n the holographic process and. other technical media. r. f One of the reasons for such a SlglL-AFg,kgiI& is that {f j the three-dimensj-onal quality of ho}ograms cannot as I yet be reprod.uced by any of the mass media. An arLj-cle and photographs published in LIFE magazine, for instance, J. PifTiiICX took great care to shovr varj-ous views of a holographic j-mage to demonstrate the three-dimensionality, but failed to make clear the fact that until you see an actual hologram, no rranner of clocumentation can illu- strate i-ts unique spatial quality. { The nunber of holograms avai-labre for peopre to view between 1964 and 1968 was very 1imitea; nofography waS When the film is developed looks a smarl and inaccessibre area it no more like a of research. t*o*"rl", picture than a gramophone record 1ooks like mrsic. But the opportunities to view holograms are now more num_ erous. The when the film is illuminated by a monochroratic light Imperial CoIIege in London has an Open Day soufce, the i-nterference pattern in May each year when the public causes the original are adrnitted, ancl in photographed object to become visible in three the ELectrical -bingineeri-ng department ther" *." usuarry horograms dimensions. .When you move your head., you can see on view. conductron corporati-on of Ann Arbor, raroundr the obJect. Michigan, has several first-rate htlograms on oisplay in their ! lobby. An exhibiti-on of horJgrams uy nait:-tns, i The one rnc., Ann fact that can record on the holographic film Arbor, toured in the autumn or l9z0-to museums I I or glass plate only what in Rochester, Syracuse 'l is illuminated with laser and Albany, after opening I at the is a fi*ilgligLintrinsic to the medium . Filch College lvluseum york, ll Lllett itself of Art, New and a similar It is a form - I of spoilight exhlbition was on view at the Exploratorium (parace illumination, with the sur- of .t rounding darkness being a black voj-d. The size of the Fine Arts) in San Francisco during the summer of I9Zl. I science I Iaser and the amount of eoherent 1ight iL gives off museums and many erectrical engineering, opticar determine the size of the illuminated area, and laser exhibitlons have examples but even of holograis. the smallest hologram will demonstrate the mediunrs unique qualiLy of three-dimensj_onal space. Some of the companies currently working in holography are: Edi-tj-ons Inco; rrow located in San Francisco; Con_ Flost holograms to date have ctuctron Corporation, Ann been of the transmlssion Arbor; T.R.W., Reciondo lieach, type. To be viewed, they need be california; Hughes Research centre, to illuminated with rviaiibu, californii; either laser light or light from a r+hite tight source and BelI Laboratories in Murray HiiI, New jersey. In ilngrand there physics which has been flltered to one particular wavelength are the Nationar Iaboratory and or color, and preferably frorn a point (a the Imperial CoJ-Iege. source srnaft opening or filament that allows most of the illumina- tion to come from one single point) so that it acquires Most holograms are monochronratic and vier*ed as though a laser-Iike quali-ty. For anyLhing larger than a {rl one were looking through a wj-ndor"r - the glass photo_ by hologram, a problem graphie plate being 5" real occurs after the holo- the window. They are made with a gram has been made. the image, a 1ight raser emitting a continuous beam of light (continuous Ig_119glggrt-e_ wave *-s,gqr-c_e*1llst- shine on the plate at the iame angle af-tia laser), using an inanimate object as Lhe subject. ieference beam For the purposes -th^9*Since- g_liginal *tien Uhe pfate wal exposed. of holographS one can think of the sriialf, inexpensive lasers are inaoequate, there laser as simpry a special light bulb, one whi-ch enri-ts a single remains the need for efficient and cheap light sources color of coherent light (figilt waves of the to illur.inate transm_issi-on holograms. sanre wavelength moving in the same dj-rection). Several general light sources To make a holopram, are currently being used an une4posed phoLographi_c film is lo replace the more expensive Laser sources for viewing. 8fitr-ffrirdYtr"*;bjecr. ii,.ri of a laser beam i1lum- For inates sharpness anci clarity, the fi_Iters have to be of the obj.ecL, and the |estrof fhe beam is deflected good quali-ty, and the brighter to the fi-]m. The the source, the more film receiveslthe wave pattern of possible it is to view holograms in a normal environ- both the cii-rect laser beam and Lh" lauu. iiglrt reflected ment, from rinterfeience thrls reduci_ng the need for stringently light- the object. The result is an paLLernr cor:,trolled areas. The white recorded on the film. light sources novi used include tensor high-intensity bulbs, microscope illum- inating lamps, quartz lodide bul_bs and the more expen- sive arc lamps. The brightness and intensity of these T \ the brain of images of human subjects that appear sources are very important because they enable a good relate precisely to the original extremely real- three-ciirnensj-onally and yeL are unreal, quality hologram to i.e. monochromatic, in color content. The eye and the subjeel netter. To have good holograms not adequately whole potenti-al of the medi-um. brain have the ability to intuitively know some of the vieirable nu1lifies the colors of a composi-tion by their Lonal rel-ationships, and the people on some occasions hologram that has a great many advantages flesh coloring of The type of seems to be rpaintedt by the eye. i" tnl'reflection hologram, ?: it needs no special point light source illuminates it viewingGurcel-A Pulsed lasers expensive and generally and' brightness' In fact, an are available only with glod definition j-n scientific laboralori-es. Consequently few holograms ordiniry light bulb ad'equately recreates the image, and portraiture is not nec"ssary to view reflection of animate objects and human have been made. because of [nis it Pulsed lasers for holograms with enough lllrrminated holograms in specially darkened areas' However, at the holograms are somewhat diffi- space to allow three-oimensj-onal portrai-ts of such sub- presEnt time reflectitn jects as an all-star football Leam, astronauts, or a cu1.t to nake. They present problems in resolution and the degree of depth and pornographic group now exist in the United StaLes only color smearing whitfr restrict aL three or four of the larger corporations.
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