Providence College DigitalCommons@Providence

Library Faculty and Staff papers Phillips Memorial Library

June 2002

3D Data Storage

Norman Desmarais Providence College, [email protected]

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Desmarais, Norman, "3D Data Storage" (2002). Library Faculty and Staff papers. 19. https://digitalcommons.providence.edu/facstaff_pubs/19

This Article is brought to you for free and open access by the Phillips Memorial Library at DigitalCommons@Providence. It has been accepted for inclusion in Library Faculty and Staff papers by an authorized administrator of DigitalCommons@Providence. For more information, please contact [email protected]. c/o Katina Strauch 209 Richardson Avenue MSC 98, The Citadel Charleston, SC 29409 SPECIAL REPRINT ™ VOLUME 14, NUMBER 3 JUNE 2002

ISSN: 1043-2094 “Linking Publishers, Vendors and Librarians” Innovations Affecting Us — 3-D Data Storage by Norman Desmarais (Acquisitions Librarian, Phillips Memorial Library, Providence College)

DVD superseded CD-ROM. Holographic data mensional object; so how can it can be recorded in a shorter “shelf life” than crystals. The crystals, on storage will eventually replace DVD. Demand for holographic images? The data is usually repre- the other hand, must be “fixed” so that the reading high-density data storage proceeds unabated; so sented as bright and dark spots, analogous to the laser does not destroy the information during the engineers continue to search for ways to pack more ones and zeroes or charged and non-charged par- reading process. Holographic storage media have data into increasingly smaller spaces. CD-ROMs ticles of conventional binary storage devices. a projected life expectancy of up to a hundred years packed 650MB of data onto a single layered disc. because they are more resistant to temperature fluc- DVD found a way to put two layers on the same The Big Picture tuations, water, acid, and electrical fields than tra- side of a disc. In addition to doubling capacity, it A single hologram can store a very large ditional storage media. was the first three-dimensional storage medium. amount of data because each “page” is recorded By putting two layers on each side, DVD can de- at a different angle relative to the plate. To read Fluorescent Multilayer Discs liver up to 9GB of data. Holography promises to each page requires illuminating the hologram One effort at holographic data storage uses fluo- increase the number of information layers to ten with a laser beam focused at the same wave- rescent multilayer discs (FMD) developed by Con- and, eventually, to 100 or more. Holographic data length, angle and polarization as the original stellation 3D Inc. (C3D) in New York. FMD tech- storage differs from conventional storage tech- reference beam. In other words, the address of nology uses fluorescent dye instead of the reflective niques in that it uses the entire volume of the re- the data is the angle and frequency of the refer- and semi-reflective coatings used by CD-ROMs cording medium, rather than just the surface, ence beam. Rotating the beam slightly — as little and DVDs. They can support up to ten informa- thereby greatly increasing potential data density. as 1000th of a degree — allows recording a fresh tion layers on each side of a disc and match the A hologram is created by splitting a laser beam “page” in the same hologram. density and transfer speeds of DVD. in two. One portion of the beam illuminates an Holograms have a particular advantage in that The fluorescent dye allows the laser beam to object with coherent light in which all the waves they allow information retrieval with only partial travel deeper into the medium with less noise travel in phase with one another. The other portion information about the original content. The read- (stray light) and interference in the return sig- of the same beam, called the reference beam, is ing mechanism retrieves and transfers an entire nal because when the focused laser strikes a pit directed at the photographic plate simultaneously, “page” of data from the storage medium at a single on one of the information layers, the fluores- but it is reflected by a mirror or prism. Because the time. A beam with only a partial image is suffi- cent light that’s reflected has a higher wave- two beams take different paths, they are no longer cient to reconstruct a reference beam that can pro- length than the laser. In other optical media, in phase with each other when they reach the film vide the address of the stored information content more layers produce more stray light, making it that corresponds most closely with the partial in- and interfere. This interference pattern is recorded difficult to distinguish the signal from the noise, put information. This is significant for image-based on the film and constitutes the hologram. To re- particularly if the noise is the same wavelength as construct (view) the image requires illuminating data sets because they are difficult to process us- ing relational database techniques. Holography the signal. With fluorescent multilayer discs, the the hologram with a light shining from the same fluorescent light carries the information; and the direction as the reference beam. The interference permits searching a large volume of data simul- taneously resulting in very fast data search rates. read device filters out the stray light and only reads pattern (hologram) diffracts this light to reconstruct the signal. This configuration permits the use of the light patterns from the original scene, render- Rates of up to 100GB/s have been demonstrated under experimental conditions. more information layers because it’s better able to ing the original surface pattern of the object in three distinguish the signal from the noise. dimensions. Developers have focused on two types of stor- While the cost of a single FMD will probably This works fine for images of objects; but digi- age material. One approach uses a photorefractive be higher than that of other storage media, the cost tal data is not ferro-electric crystal (lithium niobate). The other per gigabyte should be considerably lower if the a three-di- uses azobenzene polyesters in the form of an amor- phous or liquid crystal. However, both the photo- FMDs now in development can hold the projected polymer and crystal methods have their prob- 140GB of data. In contrast, the next-generation of lems. The material must be sensitive enough for DVDs are expected to contain 20GB. a low-powered laser to read and write on it but InPhase has a prototype hologram disc the size not so sensitive that the laser does not obliterate of a CD that can hold up to 400GB of data and data in the retrieval process. The photopolymers retrieve it at the rate of about 30MB per second. enjoy high photosensitivity, high dynamic range, continued on page 85 and ease of processing for display; but they have

84 Against the Grain / Special Reprint — June 2002 useful capacity, transfer rate, and access time. Innovations Affecting Us A holographic data storage system also has to “Linking from page 84 be cost-competitive at the same time it delivers improved performance over other conventional Publishers, Vendors That’s roughly equivalent to downloading a DVD optical and magnetic drives. and Librarians” movie in about thirty seconds. IBM is developing a system that stores 250GB in a hologram no larger Crystal Ball than a square inch. Another approach proposes to use Holographic data storage has a bright future as a photosensitive crystal the size and shape of a sugar smaller and more powerful lasers get developed. cube to store 1 terabyte of data. It can expect competition from other optical stor- The Photorefractive Information Storage age technologies, particularly DVD, which may Materials consortium (PRISM) and the Holo- employ some kind of volumetric storage scheme. Uncommon ... graphic Data Storage System consortium This could entail the use of multilayer discs or even (HDSS), under the aegis of the Defense Advanced a holographic approach to increase data-storage Against the Grain is your key to Research Projects Agency (DARPA) have been capacity. Data transfer rates of multilayer technolo- the latest news about libraries, publishers, book jobbers, and experimenting with the development of new and gies are much lower than those of holographic sys- subscription agents. ATG is a improved holographic media, spatial light modu- tems; so DVD may rely on blue-laser technology, unique collection of reports on the lators, and detector arrays, as well as the opto-me- holography, or a combination of both. issues, literature, and people that chanical components needed for high performance Holographic data storage will require a new and impact the world of books, journals, system implementations. costly manufacturing infrastructure to meet mar- ket demands for competitively priced products in and electronic information. Blue Light Specials sufficient quantity and quality. Polymer-based sys- All of the technologies discussed so far use tems may be the first on the market because they red lasers. Scientists have also been working to leverage the existing manufacturing infrastructure develop devices that use blue lasers that have better than the crystal-based, all-solid-state devices. shorter wavelengths and, consequently, greater They also allow write speeds 100 to 1,000 times storage capabilities. The blue lasers would burn faster than those using crystals. smaller pits to cram more data onto the storage Holographic devices may eventually appear in medium. That would be comparable to shrink- Unconventional ... all kinds of small portable appliances and electronic ATG is published six times a year, in ing car sizes and parking them closer together devices, such as mobile phones, handheld com- to increase the capacity of a parking lot. How- February, April, June, September, puters, video recorders, PCs, digital cameras, and November, and December/January. A ever, blue-laser devices haven’t made it out of high-definition TVs. They also offer great portabil- the laboratory because they remain too unwieldy six issue subscription is available for ity as they permit storing gigabytes of data on a only $40 U.S. ($50 Canada, $70 for commercial applications. The main problem disc the size and shape of a credit card. is that the heat they generate makes blue lasers foreign), making it an uncommonly very difficult to function reliably at room tem- good buy for all that it covers. Make checks payable to Against the Grain, perature; but Jan Oosterveld, a member of References Philips Electronics NV’s group management LLC and mail to: Buderi, Robert. Data holograms. Upside. Katina Strauch committee says: “We are not so far away from 11:6 Jun 1999 p.146. producing blue-laser DVDs in mass quantities.” 209 Richardson Avenue High density, high performance optical data MSC 98, The Citadel Sony, Matsushita Electric Industrial, storage via volume holography: viability at Charleston, SC 29409

Hitachi, Pioneer, Sharp, Samsung Electron- last? ○○○○○○○○○○○○ ics, LG Electronics, and Thomson Multime- Wilson, W. L.; Curtis, K.; Harris, A., et al. ○○○○○ dia have recently agreed on uniform standards Optical and Quantum Electronics. 32: 3, for next-generation blue-laser DVDs which may 2000 pp. 393-404. appear as early as next year. These new discs Matlis, Jan. Fluorescent multilayer discs promise capacities of up to 27GB on one side of promise to provide 1406B of storage in the a single 12cm disc — enough to store more than space of a CD. Computerworld. 35:15 pp. two hours of digital high-definition motion 56 ss. video. That’s nearly six times the 4.7GB capac- Orlov, Sergei S. Volume holographic data ity of current DVDs. storage. Association for Computing Machin- The key factors that will determine the suc- ery. Communications of the ACM. 43:11 (Nov, 2000), pp. 47-54. cess of a holographic data storage system are:

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