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Data for HVD

  1. 1. Holographic Versatile Disc 1. INTRODUCTIONHolographic Versatile Disc (HVD) is an optical disc technology which would hold up to 3.9terabytes (TB) of information. It employs a technique known as collinear holography,whereby two lasers one red and one green are collimated in a single beam. The green laser reads data encoded as laser interference fringes from a holographiclayer near the top of the disc while the red laser is used as the reference beam and to readservo information from a regular CD-style aluminium layer near the bottom. Servo information is used to monitor the position of the read head over the disc, similarto the head, track, and sector information on a conventional hard disk drive. On a CD or DVDthis servo information is interspersed amongst the data. Fig. 1.1 HVDs 1
  2. 2. Holographic Versatile Disc1.1 Definition: The Holographic Versatile Disc (HVD) is an optical disc technology developed between April 2004 and mid-2008 that can store up to several terabytes of data on an optical disc the same size as a CD, DVD or Blu-ray disc. It employs a technique known as collinear holography, whereby a green and red laser beam are collimated in a single beam. The green laser reads data encoded as laser interference fringes from a holographic layer near the top of the disc. A red laser is used as the reference beam to read servoinformation from a regular CD-style aluminium layer near the bottom1.2 Overview: Current optical DATA STORAGE media, such as the CD and DVD store data as a series of reflective marks on an internal surface of a disc. In order to increase storage capacity, it is possible for discs to hold two or even more of these data layers, but their number is severely limited since the addressing laser interacts with every layer that it passes through on the way to and from the addressed layer. These interactions cause noise that limits the technology to approximately 10 layers. 3D optical data storage methods circumvent this issue by using addressing methods where only the specifically addressed VOXEL volumetric pixel) interacts substantially with the addressing light. This necessarily involves nonlinear data reading and writing methods, in particular nonlinear optics. 3D optical data storage is related to (and competes with) holographic data storage. Traditional examples of holographic storage do not address in the third dimension, and are therefore not strictly "3D", but more recently 3D holographic storage has been realized by the use of microholograms. Layer selection multilayer technology (where a multilayer disc has layers that can be individually activated e.g. electrically) is also closely related. Fig1.2 3D_optical_storage_cross-section 2
  3. 3. Holographic Versatile DiscSchematic representation of a cross-section through a 3D optical storage disc (yellow) along adata track (orange marks). Four data layers are seen, with the laser currently addressing thethird from the top. The laser passes through the first two layers and only interacts with thethird, since here the light is at a high intensity. As an example, a prototypical 3D optical data storage system may use a disk that looksmuch like a transparent DVD. The disc contains many layers of information, each at adifferent depth in the media and each consisting of a DVD-like spiral track. In order to recordinformation on the disc a laser is brought to a focus at a particular depth in the media thatcorresponds to a particular information layer. When the laser is turned on it causes aphotchemical change in the media. As the disc spins and the read/write head moves along aradius, the layer is written just as a DVD-R is written. The depth of the focus may then bechanged and another entirely different layer of information written. The distance betweenlayers may be 5 to 100 micrometers, allowing >100 layers of information to be stored on asingle disc. In order to read the data back (in this example), a similar procedure is used except thistime instead of causing a photochemical change in the media the laser causes fluorescence.This is achieved e.g. by using a lower laser power or a different laser wavelength. Theintensity or wavelength of the fluorescence is different depending on whether the media hasbeen written at that point, and so by measuring the emitted light the data is read. The size of individual chromophore molecules or photoactive color centers is muchsmaller than the size of the laser focus (which is determined by the diffraction limit). The lighttherefore addresses a large number (possibly even 10 9) of molecules at any one time, so themedium acts as a homogeneous mass rather than a matrix structured by the positions ofchromophores. 3
  4. 4. Holographic Versatile Disc 2. HistoryThe origins of the field date back to the 1950s, when Yehuda Hirshberg developed thephotochromic apyropyrance and suggested their use in data storage. In the 1970s, ValerieBarachevskii demonstrated that this phototropism could be produced by two-photonexcitation, and finally at the end of the 1980s Peter T. Rentzepis showed that this could leadto three-dimensional data storage. This proof-of-concept system stimulated a great deal ofresearch and development, and in the following decades many academic and commercialgroups have worked on 3D optical data storage products and technologies. Most of thedeveloped systems are based to some extent on the original ideas of Rentzepis. A wide rangeof physical phenomena for data reading and recording have been investigated, large numbersof chemical systems for the medium have been developed and evaluated, and extensive workhas been carried out in solving the problems associated with the optical systems required forthe reading and recording of data. Currently, several groups remain working on solutions withvarious levels of development and interest in commercialization. 4
  5. 5. Holographic Versatile Disc 3. CONSTRUCTIONDevelopments in this area deal with many firms, for example, Japans Optware, but to date thegreatest success achieved founded in December 2000 by Lucent Technologies companyInPhase, which was able with the help of modern materials to realize the possibility ofholography on a new technical level. New realization of holographic technology, also known as "holographic memory",allows you to record 300 GB drive for information about ten times faster than modernrecording devices on conventional DVD - claimed the writing speed reaches 160 Mbit / s! Intheory, technology, to establish which InPhase announced in 2001, provides an opportunity towrite to disk 1.6 terabytes of data, and the writing speed of up to 960 Mbps, but so far onlymethod of production of spent carriers fewer and more simple equipment . According tospecialists, for one disc can be to write more than 240 hours in a televised video quality, morethan 18 months of radio broadcasts to 1.6 million high-resolution digital photos, or 780million pieces of A4 paper with the text, which is comparable with the library, consisting offour million volumes. Fig 3.1 Optical Media RecorderWheels used for holographic recording, slightly more than the diameter of traditional opticalmedia - not their diameter is 12, and 13.3 cm, more precisely, 5.25 inches. In addition, thenew drives a little thicker than normal DVD. Wheels are placed in protective plastic cartridge- recording and playback is done without extracting the holders of those cartridges. The principle of recording holographic disc, according to InPhase Technologies, Thelight laser beam is divided into two flow: signaling, which, actually, and passes usefulinformation and reference for performing official duties. In the place where these flowsintersect in recordable media, and a hologram. 5
  6. 6. Holographic Versatile Disc Fig 3.2 Process Of Storing Data Encoding data in signal stream is made using the so-called spatial light modulator(SLM), which transforms data from binary code, consisting of zeros and ones in the opticalmatrix of light and dark pixels, reminiscent chessboard. Data merged into arrays or order pagevolume million bits, the exact number is determined by modulator SLM. The intersection of reference and signal flows formed hologram recorded in thephotosensitive layer media: in the places where the projected light pixels optical matrix, thechemical reaction takes place, resulting in record holograms and implemented. By changingthe angle of the reference flow, the wavelength or position of the medium in the same sitephotosensitive material can be written many different holograms. This method "multiplex"record made it possible to significantly increase the density recording, and, consequently, thepotential capacity of the carrier. According to the developer, is currently recording densityusing a Blu laser with a wavelength of 407 nanometers is more than 250 gigabytes per squareinch. The principle of reading the data also very simple: the reference beam, aiming at thevehicle, reflects from the hologram and reconstructed the recorded information which isprojected to an array of sensors that can read data in parallel from multiple holograms. Inparallel use of reading and lay a secret high-speed data transmission. 6
  7. 7. Holographic Versatile Disc Fig 3.3 Recover Data Holograms The main challenge facing developers of InPhase Technologies, a search for suitablematerial for data storage. Scientists from Bell Labs worked on this material for seven years,and the result of their research was the material with brand names Tapestry, featuring highphotosensitivity, wide dynamic range, optical transparency, stability and spatial thermalcharacteristics as well as easy to manufacture. This material and used the company InPhaseTechnologies, isolated in their time of Bell Labs. The disadvantage of the holders on the base polymer materials is a compression seal orlimiting the amount of data that could be placed on every cubic centimeter. The submissionTapestry walked around this problem this way: this photopolymer consists of a mixture of twocompatible, but regardless polymerization chemical components. Wheels are formed bynatural polymerization one of the components, thus creating molecular grid serving as asupporting environment. Another, photosensitive component does not pass phasepolymerization and dissolves in the lattice, making geometric stability achieved during therecording of data and durability.InPhase and specialists have developed a special process ZeroWave, providing flat productionof optical media at minimal cost, which will enable these carriers to be competitive in themass market. Have been solved and a number of other problems hindering the commercial use ofholographic recording. In particular, was expanded working temperature range of recording 7
  8. 8. Holographic Versatile Disclayer, and in the recording and readers have been applied widespread inexpensive laser headwith a red and Blu laser. An array of sensors in new technology were serially producesKPOM-matrix, which are fitted with digital cameras and of high quality along with anacceptable price. In the role of spatial light modulators (SLM) played a digital micro-mirrorand ferro-electric modulators used in digital TV and video. Guaranteed term storage of dataon new media has been brought up to 50 years, which is comparable with conventional CD-RW, claimed the longevity of 20 to 100 years, depending on the manufacturer. Fig 3.4 Storage Technique Representatives called InPhase Technologies mass merits of new technology, due to thefact that on a small disk can store such volumes of data that today can be stored on multiplehard drive expensive servers. One of the applications of holographic disks is, of course,professional videotape, because these disks allow capture, edit, store and distribute video onthe same media. Holographic technology provides a new level of copyright protection for digitalcontent: storage of data on full-depth recording layer complicates pirated discs replication,and to verify the authenticity of the disk with the film or computer game can be usedholographic "watermarks". The first television network that broadcasts videotape provided with holographic disc,developed by InPhase Technologies, became a U.S. company Turner Network Television.October 21, 2005 engineers of both companies on the disk, made by Hitachi Maxell,advertisement of new technology. Advertising has been electronically read and transferred tothe server Turner Network Television, which issued after the broadcast in a strictly scheduledtime. In addition, the movie remains active and will be issued a broadcast to anyone who willseek our schedule this cable network. The first public demonstration of holographic disks inJapan was held at the International Broadcast Equipment Exhibition (InterBEE), held from 16to18November in Tokyo. Companies In Phase Technologies and Hitachi Maxell announced that the new media,as well as recording and reproducing devices already available on the market in October 2006. 8
  9. 9. Holographic Versatile DiscFirst, selling CDs with the possibility of a one-time record volume of 300 GB, by the end of2007 container carriers planned to bring up to 800 gigabytes, and by 2010 - up to 1.6terabytes. Meanwhile, all the family will be back compatible. According to the ExecutiveDirector In Phase Technologies Nelson Diaz, full backward compatibility is extremelyimportant for data storage, and this compatibility will be maintained and the rewritable discthat must be submitted in 2007. Price first recorders, estimated to representatives of thedeveloper, range from 12000 to 15000 U.S. dollars, but with the growth of sales and increasedproduction drives the price could quickly fall. Holographic discs produced by Hitachi Maxell at the Japanese factory in Tsukuba ofthe components supplied by the German chemical concern Bayer. The final price with thepossibility of a single disc recording has not yet been determined, but estimated therepresentatives of Japanese firms, it will be about 120 U.S. dollars. Money, but, with eachgigabytes of data storage will cost about 40 cents, for comparison, at 200 - gigabyte disk priceof $ 100 per gigabyte costs 50 cents. In other words, even at the stage of pilot samplesdeposited gigabytes of data at the holographic disk cheaper than todays hard drive - apromising indicator. 9
  10. 10. Holographic Versatile Disc 4. Holographic Versatile Disc Structure1. Green writing/reading laser (532 nm)2. Red positioning/addressing laser (650 nm)3. Hologram (data)4. Polycarbon layer5. Photo polymeric layer (data-containing layer)6. Distance layers7. Dichroic layer (reflecting green light)8. Aluminium reflective layer (reflecting red light)9. Transparent base P. PIT Fig 4.1 HVD Structure 4.1 Processes for creating written data Data recording in a 3D optical storage medium requires that a change take place in the medium upon excitation. This change is generally a photochemical reaction of some sort, although other possibilities exist. Chemical reactions that have been investigated include photoisomerizations, photodecomposition and photobleaching, and polymerization initiation. Most investigated have been photochromic compounds, which include azobenzenes, spiropyrans, stilbenes, fulgides and diarylethenes. If the photochemical change is reversible, then rewritable data storage may be achieved, at least in principle. Also, multilevel recording, 10
  11. 11. Holographic Versatile Disc where data is written in ‘greyscale’ rather than as ‘on’ and ‘off’ signals, is technically feasible.4.1.1 Writing by nonresonant multiphoton absorption Although there are many nonlinear optical phenomena, only multiphoton absorption is capable of injecting into the media the significant energy required to electronically excite molecular species and cause chemical reactions. Two-photon absorption is the strongest multiphoton absorbance by far, but still it is a very weak phenomenon, leading to low media sensitivity. Therefore, much research has been directed at providing chromophores with high two-photon absorption cross-sections. Writing by 2-photon absorption can be achieved by focusing the writing laser on the point where the photochemical writing process is required. The wavelength of the writing laser is chosen such that it is not linearly absorbed by the medium, and therefore it does not interact with the medium except at the focal point. At the focal point 2-photon absorption becomes significant, because it is a nonlinear process dependent on the square of the laser fluence. Fig 4.2 Layers Of Disc Writing by 2-photon absorption can also be achieved by the action of two lasers in coincidence. This method is typically used to achieve the parallel writing of information at once. One laser passes through the media, defining a line or plane. The second laser is then directed at the points on that line or plane that writing is desired. The coincidence of the lasers at these points excited 2-photon absorption, leading to writing photochemistry.4.1.2 Writing by sequential multiphoton absorption Another approach to improving media sensitivity has been to employ resonant two-photon absorption (also known as "1+1" or "sequential" 2-photon absorbance). Nonresonant two- photon absorption (as is generally used) is weak since in order for excitation to take place, the two exciting photons must arrive at the chromophore at almost exactly the same time. This is 11
  12. 12. Holographic Versatile Disc because the chromophore is unable to interact with a single photon alone. However, if the chromophore has an energy level corresponding to the (weak) absorption of one photon then this may be used as a stepping stone, allowing more freedom in the arrival time of photons and therefore a much higher sensitivity. However, this approach results in a loss of nonlinearity compared to nonresonant 2-photon absorbance (since each 1-photon absorption step is essentially linear), and therefore risks compromising the 3D resolution of the system. 4.1.3 Microholography In microholography, focused beams of light are used to record submicrometre-sized holograms in a photorefractive material, usually by the use of collinear beams. The writing process may use the same kinds of media that are used in other types of holographic data storage, and may use 2-photon processes to form the holograms. 4.1.4 Data recording during manufacturing Data may also be created in the manufacturing of the media, as is the case with most optical disc formats for commercial data distribution. In this case, the user can not write to the disc - it is a ROM format. Data may be written by a nonlinear optical method, but in this case the use of very high power lasers is acceptable so media sensitivity becomes less of an issue. The fabrication of discs containing data molded or printed into their 3D structure has also been demonstrated. For example, a disc containing data in 3D may be constructed by sandwiching together a large number of wafer-thin discs, each of which is molded or printed with a single layer of information. The resulting ROM disc can then be read using a 3D reading method. 4.2 Processes for reading data The reading of data from 3D optical memories has been carried out in many different ways. While some of these rely on the nonlinearity of the light-matter interaction to obtain 3D resolution, others use methods that spatially filter the medias linear response. Reading methods include: Two photon absorption (resulting in either absorption or fluorescence). This method is essentially two-photon microscopy. Linear excitation of fluorescence with confocal detection. This method is essentially confocal laser Scanning microscopy. It offers excitation with much lower laser powers than does two- photon absorbance, but has some potential problems because the addressing light interacts with many other data points in addition to the one being addressed. Measurement of small differences in the refractive index between the two data states. This method usually employs a phase contrast microscope or confocal reflection microscope. No absorption of light is necessary, so there is no risk of damaging data while reading, but the 12
  13. 13. Holographic Versatile Disc required refractive index mismatch in the disc may limit the thickness (i.e. number of data layers) that the media can reach due to the accumulated random wavefront errors that destroy the focused spot quality. Second harmonic generation has been demonstrated as a method to read data written into a poled polymer matrix. Optical coherence tomography has also been demonstrated as a parallel reading method. 13
  14. 14. Holographic Versatile Disc 5. Media design The active part of 3D optical storage media is usually an organicpolymer either doped or grafted with the photochemically active species. Alternatively, crystalline and sol-gel materials have been used.5.1 Media form factor Media for 3D optical data storage have been suggested in several form factors:  Disc. A disc media offers a progression from CD/DVD, and allows reading and writing to be carried out by the familiar spinning disc method.  Card. A credit card form factor media is attractive from the point of view of portability and convenience, but would be of a lower capacity than a disc.  Crystal, Cube or Sphere. Several science fiction writers have suggested small solids that store massive amounts of information, and at least in principle this could be achieved with 3D optical data storage. 5.2 Media manufacturing The simplest method of manufacturing - the molding of a disk in one piece - is a possibility for some systems. A more complex method of media manufacturing is for the media to be constructed layer by layer. This is required if the data is to be physically created during manufacture. However, layer-by-layer construction need not mean the sandwiching of many layers together. Another alternative is to create the medium in a form analogous to a roll of adhesive tape. 14
  15. 15. Holographic Versatile Disc 6. Drive design A drive designed to read and write to 3D optical data storage media may have a lot in common with CD/DVD drives, particularly if the form factor and data structure of the media is similar to that of CD or DVD. However, there are a number of notable differences that must be taken into account when designing such a drive, including: Laser. Particularly when 2-photon absorption is utilized, high-powered lasers may be required that can be bulky, difficult to cool, and pose safety concerns. Existing optical drives utilize continuous wavediode lasers operating at 780 nm, 658 nm, or 405 nm. 3D optical storage drives may require solid-state lasers or pulsed lasers, and several examples use wavelengths easily available by these technologies, such as 532 nm (green). These larger lasers can be difficult to integrate into the read/write head of the optical drive. Variable spherical aberration correction. Because the system must address different depths in the medium, and at different depths the spherical aberration induced in the wavefront is different, a method is required to dynamically account for these differences. Many possible methods exist that include optical elements that swap in and out of the optical path, moving elements, adaptive optics, and immersion lenses. Optical system. In many examples of 3D optical data storage systems, several wavelengths (colors) of light are used (e.g. reading laser, writing laser, signal; sometimes even two lasers are required just for writing). Therefore, as well as coping with the high laser power and variable spherical aberration, the optical system must combine and separate these different colors of light as required. Detection. In DVD drives, the signal produced from the disc is a reflection of the addressing laser beam, and is therefore very intense. For 3D optical storage however, the signal must be generated within the tiny volume that is addressed, and therefore it is much weaker than the laser light. In addition, fluorescence is radiated in all directions from the addressed point, so special light collection optics must be used to maximize the signal. Data tracking. Once they are identified along the z-axis, individual layers of DVD-like data may be accessed and tracked in similar ways to DVD discs. The possibility of using parallel or page-based addressing has also been demonstrated. This allows much faster data transfer rates, but requires the additional complexity of spatial light modulators, signal imaging, more powerful lasers, and more complex data handling. 15
  16. 16. Holographic Versatile Disc 7. How Holographic Memory WorkDevices that use light to store and read data have been the backbone of data storage for nearlytwo decades. Compact discs revolutionized data storage in the early 1980s, allowing multi-megabytes of data to be stored on a disc that has a diameter of a mere 12 centimeters and athickness of about 1.2 millimetres. In 1997, an improved version of the CD, called a digitalversatile disc (DVD), was released, which enabled the storage of full-length movies on asingle disc. Fig 7.1 Complete Hologram CDs and DVDs are the primary data storage methods for music, software, personalcomputing and video. A CD can hold 783 megabytes of data, which is equivalent to about onehour and 15 minutes of music, but Sony has plans to release a 1.3-gigabyte (GB) high-capacity CD. A double-sided, double-layer DVD can hold 15.9 GB of data, which is abouteight hours of movies. These conventional storage mediums meet todays storage needs, butstorage technologies have to evolve to keep pace with increasing consumer demand. CDs,DVDs and magnetic storage all store bits of information on the surface of a recordingmedium. In order to increase storage capabilities, scientists are now working on a new opticalstorage method, called holographic memory, that will go beneath the surface and use thevolume of the recording medium for storage, instead of only the surface area. 16
  17. 17. Holographic Versatile Disc 8. Basics of Holographic Memory The first step in understanding holographic memory is to understand what "holographic"means. Holography is a method of recording patterns of light to produce a three-dimensionalobject. The recorded patterns of light are called a hologram. The process of creating a hologram begins with a focused beam of light -- a laser beam.This laser beam is split into two separate beams: a reference beam, which remains unchangedthroughout much of the process, and an information beam, which passes through an image.When light encounters an image, its composition changes . In a sense, once the informationbeam encounters an image, it carries that image in its waveforms. When these two beamsintersect, it creates a pattern of light interference. If you record this pattern of lightinterference -- for example, in a photosensitive polymer layer of a disc -- you are essentiallyrecording the light pattern of the image. Fig 8.1 3-D image of the Death Star created by holography To retrieve the information stored in a hologram, you shine the reference beamdirectly onto the hologram. When it reflects off the hologram, it holds the light pattern of theimage stored there. You then send this reconstruction beam to a CMOS sensor to recreate theoriginal image. Most of us think of holograms as storing the image of an object, like the Death Starpictured above. The holographic memory systems were discussing here use holograms tostore digital instead of analog information, but its the same concept.Instead of the informationbeam encountering a pattern of light that represents the Death Star, it encounters a pattern oflight and dark areas that represent ones and zeroes. 17
  18. 18. Holographic Versatile Disc Fig 8.2 Encoded page data HVD offers several advantages over traditional storage technology. HVDs canultimately store more than 1 terabyte (TB) of information -- thats 200 times more than asingle-sided DVD and 20 times more than a current double-sided Blu-ray. This is partly dueto HVDs storing holograms in overlapping patterns, while a DVD basically stores bits ofinformation side-by-side. HVDs also use a thicker recording layer than DVDs -- an HVDstores information in almost the entire volume of the disc, instead of just a single, thin layer. The other major boost over conventional memory systems is HVDs transfer rate of upto 1 gigabyte (GB) per second -- thats 40 times faster than DVD. An HVD stores andretrieves an entire page of data, approximately 60,000 bits of information, in one pulse oflight, while a DVD stores and retrieves one bit of data in one pulse of light. 18
  19. 19. Holographic Versatile Disc 9. Blu Ray Fig 9.1 Blu RayBlu Ray is one of the newest methods in which people can enjoy media such as movies andconcerts from the comfort of their own home. Since the release of Blu Ray, a battle has wagedbetween HD DVD and Blu Ray of which has a higher quality and more enjoyable experience.However, the big question that people often ask when thinking about getting a Blu Ray playeris simple.9.1 How Does Blu Ray Work?Before answering how it works, it is important to understand why it is the superior disk. Tobegin with, a Blu Ray disk can hold up to 27 GB of data. This means that it can hold up to 2hours of a high definition movie. Regular DVDs can’t do that. They can hold only about 4.7GB of data. In other words, a standard DVD can only hold enough for a regular movie letalong a high definition. The reason for this is because of the design of the Blu Ray disk and the type of laserthat is used. Unlike a DVD which uses a red laser, Blu Ray–hence the name–uses a Blu laser.Because the Blu laser has a shorter wavelength (405 nanometers) in comparison to the redlaser which has a longer wavelength (650 nanometers), the Blu laser is able to focus better onindividual pits. The pit of a disk is where the data is stored. The more pits that a disk has andthe closer together that they are, the more data a disk can store. In other words, more pitsequals more data. The problem with DVD was that their red laser couldn’t read the pits thatwere so close together so they needed to be bigger. Unfortunately, this reduced the amount ofspace that a DVD could hold. 19
  20. 20. Holographic Versatile Disc For example, a Blu Ray laser is able to read a pit that is 0.15 microns in size. This istwo times smaller than the average size pit that a red laser can read. When spread out on anaverage Blu Ray disk, it’s easy to understand why Blu Ray is able to hold more information.Because it can hold more information and because the laser can be so accurate and focused,the picture that comes up on the television is more precise. So, a Blu Ray player works by hitting the individual pits on a Blu Ray disk with ahighly targeted Blu laser. Because of its short wave length, it can be more focused than thered laser used by a DVD player. Therefore, the quality is greater and the amount that can bestored on the disk is greater. 20
  21. 21. Holographic Versatile Disc 10. ApplicationsWhile holographic storage is currently mostly theoretical, several working models havealready been produced. Future versions of holographic storage devices will have manydifferent functions. For example, holographic storage devices will be able to store largeamounts of information for extremely long periods of time and access files at extremely highspeeds. This means that both commercial and domestic users will be able to archive files andpreserve them without worrying about losing their data. Additionally, holographic storagedevices will be able to use their high transfer rates and large storage capabilities to performcomplex calculations at much faster speeds than any supercomputer today. 21
  22. 22. Holographic Versatile Disc 11.Advantages & DisadvantagesAdvantages:11.1 Storage Capacity The most important advantage of the Holographic Versatile Disc is the increased storage capacity which is provided by the unique encoding on the discs themselves. Traditional digital discs like the CD relied on a system of grooves on the outside of the disc which were read by a laser system and turned into data. A holographic disc has several layers which a laser penetrates to create a three dimensional image which is converted to data.11.2 Transfer Rate Because more data is stored on every physical inch of a holographic disc, the transfer rate of the information is much faster than for other storage mediums. A Holographic Versatile Disc has a transfer speed of 1-gigabyte per second. This is 40 times faster than a DVD. When the device is installed in a home it provides the advantage of improved audio and video content as well as reduced load times.11.3 Backup Due to both the increased storage capacity and the increased transfer rate of Holographic Versatile Discs, the first applications for the technology could be in computer backup. The technology will initially be prohibitively expensive for most home use. This will change in time, before that however the advantages of large storage and speedy access will make the discs very useful for those in business who require the regular backup of their digital files.Disadvantages:  The initial price of the player and discs themselves are far more expensive than HD-DVD or Blu-ray.  It could be argued that the public is not entirely ready for even the costs or benefits of Blu- ray or HD-DVD, much less HVD. 22
  23. 23. Holographic Versatile Disc 12. Manufacturers1. CMC Magnetics Corporation2. FUJI PHOTO FILM CO. LTD.3. Nippon Paint Co., Ltd.4. Optware Corporation5. Pulstec Industrial Co., Ltd.6. TOAGOSEI CO., LTD. Advocates of "Holographic Versatile Disc (HVD)" announced today to form "HVD Alliance" to accelerate the development of HVD, to develop a marketplace and to promote this revolutionary technology and products. A technical committee, TC44 to discuss the standardization of "Holographic Versatile Disc (HVD)" was approved at 88th Ecma International General Assembly on December 9th 2004. The first TC44 meeting will be held in Tokyo on March 3rd and 4th. 23
  24. 24. Holographic Versatile Disc 13. Photography Vs HolographyIn photography, one is concerned only with the brightness or irradiance distribution (square ofthe amplitude) of the image. The optical path to different parts of the object is not recorded asthe photographic emulsion is a square law detector and records only the amplitude. In holography, the aim is to record complete wave field (both amplitude and phase) as itis intercepted by a recording medium. The recording plane may not be even an image plane.The scattered or reflected light by the object is intercepted by the recording medium andrecorded completely in spite of the fact that the detector is insensitive to the phase differencesamong the various parts of the optical field.In 1948 Denis Gabor gave an ingenious solution to the problem of recording phaseinformation by means of a background wave, which converts phase differences into intensitydifferences. He introduced a two step lensless imaging process known as wavefrontreconstruction technique or holography (Greek word holos means whole, complete), in whichan interference between the object field and the background wave (known as reference wave)is formed and recorded on a photographic material. The record known as a hologram (wholerecord) captures the complete wave which can be viewed at a later time by illuminating thehologram with an appropriate light beam. Thus, in holography an interference between the light reflected and scattered by theobject, called the object (signal) beam and a reference beam is created and recorded on aphotographic emulsion. If the amplitude of the signal beam remains constant and the anglebetween the beams increases, the fringes will become finer. On the other hand, if the phaserelation between the two interfering beams remain constant but the amplitude of the objectbeam changes, the contrast of the fringes will change. By this process the complex objectinformation gets coded in the form of complicated fringe pattern.The object can be considered to be made up of a large number of point sources distributed in athree dimensional space. Each point of the object will interfere with the reference and producefringes. The fringe patterns generated by different points will be varying in orientation,contrast and spacing. Gabor showed the applicability of this new process of wavefront recording by using amercury discharge lamp and taking collinear object and reference beams. The original in-linetechnique of Gabor produces both virtual and real images on the same axis, thus an observerfocussing on one image, always sees it accompanied by the out-of-focus twin image. 24
  25. 25. Holographic Versatile Disc 14. Available in MarketNow available on 1 terabyte to 5 terabyte drives and media.1 tera byte to 5 terabyte drives has been officially released today.Priced at $199 US for the burner drives for computers.1 tera byte media $9.95 US.2 tera byte media $14.95 US.3 tera byte media $19.95 US.4 tera byte media $24.95 US.5 tera byte media $29.95 US. The computer drives run on sata 2 connections and push data through atup to 300Mb / sec which is many times faster than the current drivescan move data or videoto. Terabyte players which are backward compatible with dvd players have the price set at$399 US. These players will record and play to divxmedia. HDV has turned their nose at copy protection. They will not be bulliedby Hollywood. It is thought the new way of storage will revolutionizethe industry. Hollywoodmay block this but many others will be able tobackup their large movie collection of hundredsof dvds straight toone terabyte disk. 25
  26. 26. Holographic Versatile Disc 15. ConclusionHolography Versatile Disc(HVD) is the best alternative of the DVD & VCD technologies . They haveawesome Memory storage Capacity, also they will have a better transfer rates then other technologies.It has high refresh rates with faster response time.Because of this features HVD surely going to replaceDVD & VCD technologies. Thus we have miscellaneous system working for us in future.So, what we can do is to just wait and watch for new golden year of these technology.- 26
  27. 27. Holographic Versatile Disc Bibliography disc-has-arrived.html 27