Holographic data storage
Encyclopedia
Holographic data storage is a potential technology in the area of high-capacity data
storage currently dominated by magnetic and conventional optical data storage. Magnetic and optical data storage devices rely on individual bits being stored as distinct magnetic or optical changes on the surface of the recording medium. Holographic data storage overcomes this limitation by recording information throughout the volume of the medium and is capable of recording multiple images in the same area utilizing light at different angles.
Additionally, whereas magnetic and optical data storage records information a bit at a time in a linear fashion, holographic storage is capable of recording and reading millions of bits in parallel, enabling data transfer rates greater than those attained by traditional optical storage.
beam is divided into two separate optical patterns of dark and light pixels. By adjusting the reference beam angle, wavelength, or media position, a multitude of holograms (theoretically, several thousand) can be stored on a single volume.
) approach to data storage would ensure content security, preventing the information from being overwritten or modified. Manufacturers believe this technology can provide safe storage for content without degradation for more than 50 years, far exceeding current data storage options. Counterpoints to this claim are that the evolution of data reader technology has – in the last couple of decades – changed every ten years. If this trend continues, it therefore follows that being able to store data for 50–100 years on one format is irrelevant, because you would migrate the data to a new format after only ten years. However, claimed longevity of storage has, in the past, proven to be a key indicator of shorter-term reliability of storage media. Current optical formats – such as CD – have largely lived up to the original longevity claims (where reputable media makes are used) and have proved to be more reliable shorter-term data carriers than the floppy disc and DAT
tape media they displaced.
modulation
produced per unit of exposure. Diffraction efficiency is proportional to the square of the index modulation
times the effective thickness.
The dynamic range determines how many holograms may be multiplexed
in a single volume data.
Spatial light modulator
s (SLM) are pixelated input devices (liquid crystal panels), used to imprint the data to be stored on the object beam.
in crystals:
When the information is to be retrieved or read out from the hologram, only the reference beam is necessary. The beam is sent into the material in exactly the same way as when the hologram was written. As a result of the index changes in the material that were created during writing, the beam splits into two parts. One of these parts recreates the signal beam where the information is stored. Something like a CCD
camera can be used to convert this information into a more usable form.
Holograms can theoretically store one bit
per cubic block the size of the wavelength
of light in writing. For example, light from a helium-neon laser
is red, 632.8 nm
wavelength light. Using light of this wavelength, perfect holographic storage could store 4 gigabits per cubic millimetre. In practice, the data density would be much lower, for at least four reasons:
Despite those limitations, it is possible to optimize the storage capacity using all-optical signal processing techniques
Unlike current storage technologies that record and read one data bit at a time, holographic memory writes and reads data in parallel in a single flash of light.
(green, red or IR) and the sensitizing/gating
beam is a separate, shorter wavelength (blue or UV). The sensitizing/gating beam is used to sensitize the material before and during the recording process, while the information is recorded in the crystal
via the reference and signal beams. It is shone intermittently on the crystal during the recording process for measuring the diffracted beam intensity. Readout is achieved by illumination with the reference beam alone. Hence the readout beam with a longer wavelength would not be able to excite the recombined electron
s from the deep trap centers during readout, as they need the sensitizing light with shorter wavelength to erase them.
Usually, for two-color holographic recording, two different dopants are required to promote trap centers, which belong to transition metal
and rare earth elements and are sensitive to certain wavelengths. By using two dopants, more trap centers would be created in the lithium niobate
crystal. Namely a shallow and a deep trap would be created. The concept now is to use the sensitizing light to excite electrons from the deep trap farther from the valence band
to the conduction band
and then to recombine at the shallow traps nearer to the conduction band. The reference and signal beam would then be used to excite the electrons from the shallow traps back to the deep traps. The information would hence be stored in the deep traps. Reading would be done with the reference beam since the electrons can no longer be excited out of the deep traps by the long wavelength beam.
state for desired performance. This optimum depends on the doping levels of shallow and deep traps as well as the annealing
conditions for the crystal samples. This optimum state generally occurs when 95 – 98% of the deep traps are filled. In a strongly oxidized sample holograms cannot be easily recorded and the diffraction efficiency is very low. This is because the shallow trap is completely empty and the deep trap is also almost devoid of electrons. In a highly reduced sample on the other hand, the deep traps are completely filled and the shallow traps are also partially filled. This results in very good sensitivity (fast recording) and high diffraction efficiency due to the availability of electrons in the shallow traps. However during readout, all the deep traps get filled quickly and the resulting holograms reside in the shallow traps where they are totally erased by further readout. Hence after extensive readout the diffraction efficiency drops to zero and the hologram stored cannot be fixed.
conducted public demonstrations of the world’s first prototype of a commercial storage device at the Maxell Corporation of America booth.
The three main companies involved in developing holographic memory, as of 2002, were InPhase
and Polaroid spinoff Aprilis in the United States, and Optware in Japan. Although holographic memory has been discussed since the 1960s, and has been touted for near-term commercial application at least since 2001, it has yet to convince critics that it can find a viable market.
As of 2002, planned holographic products did not aim to compete head to head with hard drives, but instead to find a market niche based on virtues such as speed of access.
InPhase Technologies, after several announcements and subsequent delays in 2006 and 2007, announced that it would soon be introducing a flagship product. InPhase went out of business in February 2010 and had its assets seized by the state of Colorado for back taxes. The company had reportedly gone through $100 million but the lead investor was unable to raise more capital.
In April 2009, GE Global Research
demonstrated their own holographic storage material that could allow for discs that utilize similar read mechanisms as those found on Blu-ray Disc
players.
will be the first video game console maker to implement holographic data storage due to the uncovering of a Joint Research Agreement between InPhase
and Nintendo
.
Nintendo
is also mentioned in the patent as a joint applicant: "... disclosure is herein made that the claimed invention was made pursuant to a Joint Research Agreement as defined in 35 U.S.C. 103 (c)(3), that was in effect on or before the date the claimed invention was made, and as a result of activities undertaken within the scope of the Joint Research Agreement, by or on the behalf of Nintendo Co., and InPhase Technologies, Inc."
It is still unclear whether InPhase's closure has affected this rumor in any way.
Data
The term data refers to qualitative or quantitative attributes of a variable or set of variables. Data are typically the results of measurements and can be the basis of graphs, images, or observations of a set of variables. Data are often viewed as the lowest level of abstraction from which...
storage currently dominated by magnetic and conventional optical data storage. Magnetic and optical data storage devices rely on individual bits being stored as distinct magnetic or optical changes on the surface of the recording medium. Holographic data storage overcomes this limitation by recording information throughout the volume of the medium and is capable of recording multiple images in the same area utilizing light at different angles.
Additionally, whereas magnetic and optical data storage records information a bit at a time in a linear fashion, holographic storage is capable of recording and reading millions of bits in parallel, enabling data transfer rates greater than those attained by traditional optical storage.
Recording data
Holographic data storage captures information using an optical interference pattern within a thick, photosensitive optical material. Light from a single laserLaser
A laser is a device that emits light through a process of optical amplification based on the stimulated emission of photons. The term "laser" originated as an acronym for Light Amplification by Stimulated Emission of Radiation...
beam is divided into two separate optical patterns of dark and light pixels. By adjusting the reference beam angle, wavelength, or media position, a multitude of holograms (theoretically, several thousand) can be stored on a single volume.
Reading data
The stored data is read through the reproduction of the same reference beam used to create the hologram. The reference beam’s light is focused on the photosensitive material, illuminating the appropriate interference pattern, the light diffracts on the interference pattern, and projects the pattern onto a detector. The detector is capable of reading the data in parallel, over one million bits at once, resulting in the fast data transfer rate. Files on the holographic drive can be accessed in less than 200 milliseconds.Longevity
Holographic data storage can provide companies a method to preserve and archive information. The write-once, read many (WORMWrite Once Read Many
A Write Once Read Many or WORM drive is a data storage device where information, once written, cannot be modified. On ordinary data storage devices, the number of times data can be modified is not limited, except by the rated lifespan of the device, as modification involves physical changes that...
) approach to data storage would ensure content security, preventing the information from being overwritten or modified. Manufacturers believe this technology can provide safe storage for content without degradation for more than 50 years, far exceeding current data storage options. Counterpoints to this claim are that the evolution of data reader technology has – in the last couple of decades – changed every ten years. If this trend continues, it therefore follows that being able to store data for 50–100 years on one format is irrelevant, because you would migrate the data to a new format after only ten years. However, claimed longevity of storage has, in the past, proven to be a key indicator of shorter-term reliability of storage media. Current optical formats – such as CD – have largely lived up to the original longevity claims (where reputable media makes are used) and have proved to be more reliable shorter-term data carriers than the floppy disc and DAT
Digital Audio Tape
Digital Audio Tape is a signal recording and playback medium developed by Sony and introduced in 1987. In appearance it is similar to a compact audio cassette, using 4 mm magnetic tape enclosed in a protective shell, but is roughly half the size at 73 mm × 54 mm × 10.5 mm. As...
tape media they displaced.
Terms used
Sensitivity refers to the extent of refractive indexRefractive index
In optics the refractive index or index of refraction of a substance or medium is a measure of the speed of light in that medium. It is expressed as a ratio of the speed of light in vacuum relative to that in the considered medium....
modulation
Modulation
In electronics and telecommunications, modulation is the process of varying one or more properties of a high-frequency periodic waveform, called the carrier signal, with a modulating signal which typically contains information to be transmitted...
produced per unit of exposure. Diffraction efficiency is proportional to the square of the index modulation
Modulation index
The modulation index of a modulation scheme describes by how much the modulated variable of the carrier signal varies around its unmodulated level. It is defined differently in each modulation scheme. See:*Amplitude modulation index...
times the effective thickness.
The dynamic range determines how many holograms may be multiplexed
Multiplexing
The multiplexed signal is transmitted over a communication channel, which may be a physical transmission medium. The multiplexing divides the capacity of the low-level communication channel into several higher-level logical channels, one for each message signal or data stream to be transferred...
in a single volume data.
Spatial light modulator
Spatial light modulator
A spatial light modulator is an object that imposes some form of spatially-varying modulation on a beam of light. A simple example is an overhead projector transparency. Usually when the phrase SLM is used, it means that the transparency can be controlled by a computer. In the 1980s, large SLMs...
s (SLM) are pixelated input devices (liquid crystal panels), used to imprint the data to be stored on the object beam.
Technical aspects
Like other media, holographic media is divided into write once (where the storage medium undergoes some irreversible change), and rewritable media (where the change is reversible). Rewritable holographic storage can be achieved via the photorefractive effectPhotorefractive effect
The photorefractive effect is a nonlinear optical effect seen in certain crystals and other materials that respond to light by altering their refractive index....
in crystals:
- Mutually coherentCoherence (physics)In physics, coherence is a property of waves that enables stationary interference. More generally, coherence describes all properties of the correlation between physical quantities of a wave....
light from two sources creates an interference pattern in the media. These two sources are called the reference beamReference beamA reference beam is a laser beam used to read and write holograms. It is one of two laser beams used to create a hologram. In order to read a hologram out, some aspects of the reference beam must be reproduced exactly as when it was used to write the hologram...
and the signal beamSignal beamA signal beam or object beam is one of at least two laser beams used to write holograms. The signal beam is the beam that carries the information to be stored in the hologram. In the case of a holographic picture, this beam is reflected off the object being recorded, into the media...
. - Where there is constructive interference the light is bright and electrons can be promoted from the valence bandValence bandIn solids, the valence band is the highest range of electron energies in which electrons are normally present at absolute zero temperature....
to the conduction bandConduction bandIn the solid-state physics field of semiconductors and insulators, the conduction band is the range of electron energies, higher than that of the valence band, sufficient to free an electron from binding with its individual atom and allow it to move freely within the atomic lattice of the material...
of the material (since the light has given the electrons energy to jump the energy gap). The positively charged vacancies they leave are called holesElectron holeAn electron hole is the conceptual and mathematical opposite of an electron, useful in the study of physics, chemistry, and electrical engineering. The concept describes the lack of an electron at a position where one could exist in an atom or atomic lattice...
and they must be immobile in rewritable holographic materials. Where there is destructive interference, there is less light and few electrons are promoted. - Electrons in the conduction band are free to move in the material. They will experience two opposing forces that determine how they move. The first force is the coulomb force between the electrons and the positive holes that they have been promoted from. This force encourages the electrons to stay put or move back to where they came from. The second is the pseudo-force of diffusionDiffusionMolecular diffusion, often called simply diffusion, is the thermal motion of all particles at temperatures above absolute zero. The rate of this movement is a function of temperature, viscosity of the fluid and the size of the particles...
that encourages them to move to areas where electrons are less dense. If the coulomb forces are not too strong, the electrons will move into the dark areas. - Beginning immediately after being promoted, there is a chance that a given electron will recombine with a hole and move back into the valence band. The faster the rate of recombination, the fewer the number of electrons that will have the chance to move into the dark areas. This rate will affect the strength of the hologram.
- After some electrons have moved into the dark areas and recombined with holes there, there is a permanent space charge fieldElectric fieldIn physics, an electric field surrounds electrically charged particles and time-varying magnetic fields. The electric field depicts the force exerted on other electrically charged objects by the electrically charged particle the field is surrounding...
between the electrons that moved to the dark spots and the holes in the bright spots. This leads to a change in the index of refractionRefractive indexIn optics the refractive index or index of refraction of a substance or medium is a measure of the speed of light in that medium. It is expressed as a ratio of the speed of light in vacuum relative to that in the considered medium....
due to the electro-optic effectElectro-optic effectAn electro-optic effect is a change in the optical properties of a material in response to an electric field that varies slowly compared with the frequency of light...
.
When the information is to be retrieved or read out from the hologram, only the reference beam is necessary. The beam is sent into the material in exactly the same way as when the hologram was written. As a result of the index changes in the material that were created during writing, the beam splits into two parts. One of these parts recreates the signal beam where the information is stored. Something like a CCD
Charge-coupled device
A charge-coupled device is a device for the movement of electrical charge, usually from within the device to an area where the charge can be manipulated, for example conversion into a digital value. This is achieved by "shifting" the signals between stages within the device one at a time...
camera can be used to convert this information into a more usable form.
Holograms can theoretically store one bit
Bit
A bit is the basic unit of information in computing and telecommunications; it is the amount of information stored by a digital device or other physical system that exists in one of two possible distinct states...
per cubic block the size of the wavelength
Wavelength
In physics, the wavelength of a sinusoidal wave is the spatial period of the wave—the distance over which the wave's shape repeats.It is usually determined by considering the distance between consecutive corresponding points of the same phase, such as crests, troughs, or zero crossings, and is a...
of light in writing. For example, light from a helium-neon laser
Helium-neon laser
A helium–neon laser or HeNe laser, is a type of gas laser whose gain medium consists of a mixture of helium and neon inside of a small bore capillary tube, usually excited by a DC electrical discharge.- History of HeNe laser development:...
is red, 632.8 nm
Nanometre
A nanometre is a unit of length in the metric system, equal to one billionth of a metre. The name combines the SI prefix nano- with the parent unit name metre .The nanometre is often used to express dimensions on the atomic scale: the diameter...
wavelength light. Using light of this wavelength, perfect holographic storage could store 4 gigabits per cubic millimetre. In practice, the data density would be much lower, for at least four reasons:
- The need to add error-correction
- The need to accommodate imperfections or limitations in the optical system
- Economic payoff (higher densities may cost disproportionately more to achieve)
- Design technique limitations—a problem currently faced in magnetic Hard Drives wherein magnetic domain configuration prevents manufacture of disks that fully utilize the theoretical limits of the technology.
Despite those limitations, it is possible to optimize the storage capacity using all-optical signal processing techniques
Unlike current storage technologies that record and read one data bit at a time, holographic memory writes and reads data in parallel in a single flash of light.
Two-color recording
For two-color holographic recording, the reference and signal beam fixed to a particular wavelengthWavelength
In physics, the wavelength of a sinusoidal wave is the spatial period of the wave—the distance over which the wave's shape repeats.It is usually determined by considering the distance between consecutive corresponding points of the same phase, such as crests, troughs, or zero crossings, and is a...
(green, red or IR) and the sensitizing/gating
Gating
-Neurobiology:*Gating , the opening or closing of ion channels*Sensory gating, an automatic process by which the brain adjusts to stimuli*Synaptic gating, neural circuits suppressing inputs through synapses...
beam is a separate, shorter wavelength (blue or UV). The sensitizing/gating beam is used to sensitize the material before and during the recording process, while the information is recorded in the crystal
Crystal
A crystal or crystalline solid is a solid material whose constituent atoms, molecules, or ions are arranged in an orderly repeating pattern extending in all three spatial dimensions. The scientific study of crystals and crystal formation is known as crystallography...
via the reference and signal beams. It is shone intermittently on the crystal during the recording process for measuring the diffracted beam intensity. Readout is achieved by illumination with the reference beam alone. Hence the readout beam with a longer wavelength would not be able to excite the recombined electron
Electron
The electron is a subatomic particle with a negative elementary electric charge. It has no known components or substructure; in other words, it is generally thought to be an elementary particle. An electron has a mass that is approximately 1/1836 that of the proton...
s from the deep trap centers during readout, as they need the sensitizing light with shorter wavelength to erase them.
Usually, for two-color holographic recording, two different dopants are required to promote trap centers, which belong to transition metal
Transition metal
The term transition metal has two possible meanings:*The IUPAC definition states that a transition metal is "an element whose atom has an incomplete d sub-shell, or which can give rise to cations with an incomplete d sub-shell." Group 12 elements are not transition metals in this definition.*Some...
and rare earth elements and are sensitive to certain wavelengths. By using two dopants, more trap centers would be created in the lithium niobate
Lithium niobate
Lithium niobate is a compound of niobium, lithium, and oxygen. Its single crystals are an important material for optical waveguides, mobile phones, optical modulators and various other linear and non-linear optical applications.-Properties:...
crystal. Namely a shallow and a deep trap would be created. The concept now is to use the sensitizing light to excite electrons from the deep trap farther from the valence band
Valence band
In solids, the valence band is the highest range of electron energies in which electrons are normally present at absolute zero temperature....
to the conduction band
Conduction band
In the solid-state physics field of semiconductors and insulators, the conduction band is the range of electron energies, higher than that of the valence band, sufficient to free an electron from binding with its individual atom and allow it to move freely within the atomic lattice of the material...
and then to recombine at the shallow traps nearer to the conduction band. The reference and signal beam would then be used to excite the electrons from the shallow traps back to the deep traps. The information would hence be stored in the deep traps. Reading would be done with the reference beam since the electrons can no longer be excited out of the deep traps by the long wavelength beam.
Effect of annealing
For a doubly doped lithium niobate (LiNbO3) crystal there exists an optimum oxidation/reductionRedox
Redox reactions describe all chemical reactions in which atoms have their oxidation state changed....
state for desired performance. This optimum depends on the doping levels of shallow and deep traps as well as the annealing
Annealing (metallurgy)
Annealing, in metallurgy and materials science, is a heat treatment wherein a material is altered, causing changes in its properties such as strength and hardness. It is a process that produces conditions by heating to above the recrystallization temperature, maintaining a suitable temperature, and...
conditions for the crystal samples. This optimum state generally occurs when 95 – 98% of the deep traps are filled. In a strongly oxidized sample holograms cannot be easily recorded and the diffraction efficiency is very low. This is because the shallow trap is completely empty and the deep trap is also almost devoid of electrons. In a highly reduced sample on the other hand, the deep traps are completely filled and the shallow traps are also partially filled. This results in very good sensitivity (fast recording) and high diffraction efficiency due to the availability of electrons in the shallow traps. However during readout, all the deep traps get filled quickly and the resulting holograms reside in the shallow traps where they are totally erased by further readout. Hence after extensive readout the diffraction efficiency drops to zero and the hologram stored cannot be fixed.
Development and marketing
At the National Association of Broadcasters 2005 (NAB) convention in Las Vegas, InPhaseInPhase Technologies
InPhase Technologies is a technology company developing holographic storage devices and media. InPhase was spun out from Bell Labs in 2000. Their technology eventually promises multiple terabyte storage. In May 2008 the company was due to release their first reader, tapestry 300r, offering a...
conducted public demonstrations of the world’s first prototype of a commercial storage device at the Maxell Corporation of America booth.
The three main companies involved in developing holographic memory, as of 2002, were InPhase
InPhase Technologies
InPhase Technologies is a technology company developing holographic storage devices and media. InPhase was spun out from Bell Labs in 2000. Their technology eventually promises multiple terabyte storage. In May 2008 the company was due to release their first reader, tapestry 300r, offering a...
and Polaroid spinoff Aprilis in the United States, and Optware in Japan. Although holographic memory has been discussed since the 1960s, and has been touted for near-term commercial application at least since 2001, it has yet to convince critics that it can find a viable market.
As of 2002, planned holographic products did not aim to compete head to head with hard drives, but instead to find a market niche based on virtues such as speed of access.
InPhase Technologies, after several announcements and subsequent delays in 2006 and 2007, announced that it would soon be introducing a flagship product. InPhase went out of business in February 2010 and had its assets seized by the state of Colorado for back taxes. The company had reportedly gone through $100 million but the lead investor was unable to raise more capital.
In April 2009, GE Global Research
GE Global Research
GE Global Research is the research and development division of General Electric.GE Global Research's primary facility is located in Niskayuna, New York. The Advanced Manufacturing and Software Technology Center is a satelite facility located in Van Buren, Michigan...
demonstrated their own holographic storage material that could allow for discs that utilize similar read mechanisms as those found on Blu-ray Disc
Blu-ray Disc
Blu-ray Disc is an optical disc storage medium designed to supersede the DVD format. The plastic disc is 120 mm in diameter and 1.2 mm thick, the same size as DVDs and CDs. Blu-ray Discs contain 25 GB per layer, with dual layer discs being the norm for feature-length video discs...
players.
In the video game market
Some have speculated that NintendoNintendo
is a multinational corporation located in Kyoto, Japan. Founded on September 23, 1889 by Fusajiro Yamauchi, it produced handmade hanafuda cards. By 1963, the company had tried several small niche businesses, such as a cab company and a love hotel....
will be the first video game console maker to implement holographic data storage due to the uncovering of a Joint Research Agreement between InPhase
InPhase Technologies
InPhase Technologies is a technology company developing holographic storage devices and media. InPhase was spun out from Bell Labs in 2000. Their technology eventually promises multiple terabyte storage. In May 2008 the company was due to release their first reader, tapestry 300r, offering a...
and Nintendo
Nintendo
is a multinational corporation located in Kyoto, Japan. Founded on September 23, 1889 by Fusajiro Yamauchi, it produced handmade hanafuda cards. By 1963, the company had tried several small niche businesses, such as a cab company and a love hotel....
.
Nintendo
Nintendo
is a multinational corporation located in Kyoto, Japan. Founded on September 23, 1889 by Fusajiro Yamauchi, it produced handmade hanafuda cards. By 1963, the company had tried several small niche businesses, such as a cab company and a love hotel....
is also mentioned in the patent as a joint applicant: "... disclosure is herein made that the claimed invention was made pursuant to a Joint Research Agreement as defined in 35 U.S.C. 103 (c)(3), that was in effect on or before the date the claimed invention was made, and as a result of activities undertaken within the scope of the Joint Research Agreement, by or on the behalf of Nintendo Co., and InPhase Technologies, Inc."
It is still unclear whether InPhase's closure has affected this rumor in any way.
See also
- Holographic Versatile CardHolographic Versatile CardThe Holographic Versatile Card is a data storage format by Optware; the projected date for a Japanese launch had been the first half of 2007, pending finalization of the specification, however as of July 2010, nothing has yet surfaced. One of its main advantages compared with discs is the lack of...
- Holographic Versatile DiscHolographic Versatile DiscThe Holographic Versatile Disc 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...
- Holographic associative memoryHolographic associative memoryHolographic Associative Memory is part of the family of analog, correlation-based, associative, stimulus-response memories, where information is mapped onto the phase orientation of complex numbers operating. It can be considered as a complex valued artificial neural network. The holographic...
- 3D optical data storage3D optical data storage3D optical data storage is the term given to any form of optical data storage in which information can be recorded and/or read with three dimensional resolution ....
- List of emerging technologies
- HolographyHolographyHolography is a technique that allows the light scattered from an object to be recorded and later reconstructed so that when an imaging system is placed in the reconstructed beam, an image of the object will be seen even when the object is no longer present...
External links
- Howstuffworks
- Daewoo Electronics Develops the World’s First High Accuracy Servo Motion Control System for Holographic Digital Data Storage (virtual prototype created with LabView)
- Inphase –
- Comparison of Two Approaches: Page-based and Bit-based HDS
- Maxell Holographic Media Press Release
- GE Global Research is developing terabyte discs and players that will work with old storage media
- Holography speaks volumes – an Instant Insight where Søren Hvilsted and colleagues explain how holograms could be the key to storing increasing amounts of information. From the Royal Society of ChemistryRoyal Society of ChemistryThe Royal Society of Chemistry is a learned society in the United Kingdom with the goal of "advancing the chemical sciences." It was formed in 1980 from the merger of the Chemical Society, the Royal Institute of Chemistry, the Faraday Society and the Society for Analytical Chemistry with a new...