Innovation: Data revolution in holograms: 3D laser images may soon offer a dramatic rise in the memory storage capacity of computers, says Philip Ball

MOST people know holograms as curious three-dimensional art forms. Now physicists at Stanford University in California have demonstrated how holograms, which are constructed from laser light, can be used to create computer memories with potentially much higher capacity than existing electronic data storage systems.

As the revolution in information technology continues to boom, computer systems are having to cope with ever-increasing amounts of data. The solution to this overload may be to store it using light rather than electronics.

Current computer technology stores data in much the same way as a library: each item of information is placed in a specific location within a data bank, like books in a library. The drawback of this approach is that as the amount of data increases, so must the volume of the library.

But for several decades now, information engineers have been dreaming of an alternative, in which items of information are more densely packed by writing them on top of each other. In conventional computer memories, data is recorded in binary code, which can be written into an array of electronic or magnetic switches that are 'on' or 'off'.

This same code is used in light-based (optical) memories where it translates into a pattern of light and dark spots, like a black-and-white image on photographic film. The advantage of optical information storage is that the patterns, each representing a piece of information - say, a person's name or a bank account number - can be superimposed in the same image-recording medium.

In effect, the data bank is like a photographic film subjected to multiple exposures. But won't the images become hard to distinguish once several have been laid on top of each other? Not if each one is stored in three dimensions within a block of light-sensitive material, rather than in the two dimensions of photographic film. Not, in other words, if the image is a hologram.

The science of holograms was developed in the 1940s by Denis Gabor, a British-Hungarian physicist. Holograms are constructed using 'coherent' light, in which all the rays can be considered as oscillating in step with each other.

Gabor showed theoretically that if a coherent light beam is split in two, one half is shone on to an object and the scattered light beam is allowed to intersect the other half of the beam, the two beams will interfere to form a spatial pattern of light and dark that is a three-dimensional image of the object: a hologram.

Gabor's ideas were realised experimentally when the invention of lasers in the 1960s made it possible to generate coherent light. A hologram contains all the visual information from the original object, so one can see the front, back and sides.

Most people have seen plenty of evidence, in exhibitions and art shops, that holo graphy works. Putting holo grams to use for optical information storage with the data density and stability required by computers is, however, another matter entirely.

Not only does one need a material that will capture holo graphic images quickly and with high fidelity, but one must be able to read that information back out, to erase it and write over it, and to link the whole affair up to the electronic circuitry of a computer. These problems are now being solved.

To write digital electronic information into a light-sensitive material, the electronic signal is used to control arrays of liquid crystal shutters which chop a laser beam into a pattern of light and dark. This processed beam then writes the data as a holographic image into the storage medium. Like a film projector converting a film into light, a second laser beam is used to read the data back out. Highly sensitive light meters called charge-coupled devices (also used in astronomy for detecting extremely faint galaxies) convert the optical signal back into electronic form.

Can a system like this be used to process information at speeds and data densities comparable to electronic computers? This was the challenge taken up by the Stanford team, led by Dr Lambertus Hesselink. In August they announced their success in developing a holo graphic storage system that writes and reads digital information when hooked up to a standard computer hard drive.

The performance of this prototype was not impressive: it was slow and could handle fewer data bytes than a floppy disk. Moreover, after reading the information out several times, the memory became corrupted.

Dr Hesselink's team is optimistic about improving the performance; it has set up a company, Optitek, and aims to have a commercial system in two to three years. The Stanford team is not alone in believing that holographic storage could solve the data storage problem. Other companies are pursuing the idea, too. The biggest obstacle is the holographic storage medium itself.

Dr Hesselink used the recording medium that has been the mainstay of optical technology for years: a crystalline material called lithium niobate. Hopes for the future are pinned on new materials made from organic polymers which will allow higher storage densities, faster writing speeds and greater ease of processing.

(Graphic omitted)

Bryan Cranston as Walter White, in the acclaimed series 'Breaking Bad'
There have been various incidents of social media users inadvertently flouting the law

footballChelsea 6 Maribor 0: Blues warm up for Premier League showdown with stroll in Champions League
Arts and Entertainment
Princess Olga in 'You Can't Get the Staff'
tvReview: The anachronistic aristocrats, it seemed, were just happy to have some attention
Life and Style

Board creates magnetic field to achieve lift

Renee Zellweger as Bridget Jones
ebooksAn unforgettable anthology of contemporary reportage
Those who were encouraged to walk in a happy manner remembered less negative words
Life and Style
Stack ‘em high?: quantity doesn’t always trump quality, as Friends of the Earth can testify
techThe proliferation of online petitions allows us to register our protests at the touch of a button. But do they change anything?
Bourgogne wine maker Laboure-Roi vice president Thibault Garin (L) offers the company's 2013 Beaujolais Nouveau wine to the guest in the wine spa at the Hakone Yunessun spa resort facilities in Hakone town, Kanagawa prefecture, some 100-kilometre west of Tokyo
CSKA Moscow celebrate after equalising with a late penalty
footballCSKA Moscow 2 Manchester City 2: Premier League champions let two goal lead slip in Russia
Sudan, the last male northern white rhino
environmentThe death of a white northern rhino in Kenya has left the species with a single male. These are the other species on the brink
Latest stories from i100
Have you tried new the Independent Digital Edition apps?
Independent Dating

By clicking 'Search' you
are agreeing to our
Terms of Use.

iJobs Job Widget
iJobs Money & Business

Helpdesk Analyst

£23000 per annum + pension and 22 days holiday: Ashdown Group: An established ...

Senior Helpdesk Analyst / Service Desk Co-ordinator

£27000 per annum + pension, 22 days holiday: Ashdown Group: An established ind...

Senior Pensions Administrator

£23000 - £26000 Per Annum: Clearwater People Solutions Ltd: Our client is curr...

Corporate Actions Administrator / Operations Administrator

£25 - 30k: Guru Careers: A Corporate Actions Administrator / Operations Admini...

Day In a Page

Indiana serial killer? Man arrested for murdering teenage prostitute confesses to six other murders - and police fear there could be many more

A new American serial killer?

Police fear man arrested for murder of teen prostitute could be responsible for killing spree dating back 20 years
Sweetie, the fake 10-year-old girl designed to catch online predators, claims her first scalp

Sting to trap paedophiles may not carry weight in UK courts

Computer image of ‘Sweetie’ represented entrapment, experts say
Fukushima nuclear crisis: Evacuees still stuck in cramped emergency housing three years on - and may never return home

Return to Fukushima – a land they will never call home again

Evacuees still stuck in cramped emergency housing three years on from nuclear disaster
Online petitions: Sign here to change the world

Want to change the world? Just sign here

The proliferation of online petitions allows us to register our protests at the touch of a button. But do they change anything?
Ed Sheeran hits back after being labelled too boring to headline festivals

'You need me, I don’t need you'

Ed Sheeran hits back after being labelled too boring to headline festivals
How to Get Away with Murder: Shonda Rhimes reinvents the legal drama

How to Get Away with Murder

Shonda Rhimes reinvents the legal drama
A cup of tea is every worker's right

Hard to swallow

Three hospitals in Leicester have banned their staff from drinking tea and coffee in public areas. Christopher Hirst explains why he thinks that a cuppa is every worker's right
Which animals are nearly extinct?

Which animals are nearly extinct?

Conservationists in Kenya are in mourning after the death of a white northern rhino, which has left the species with a single male. These are the other species on the brink
12 best children's shoes

Perfect for leaf-kicking: 12 best children's shoes

Find footwear perfect to keep kids' feet protected this autumn
Anderlecht vs Arsenal: Gunners' ray of light Aaron Ramsey shines again

Arsenal’s ray of light ready to shine again

Aaron Ramsey’s injury record has prompted a club investigation. For now, the midfielder is just happy to be fit to face Anderlecht in the Champions League
Comment: David Moyes' show of sensitivity thrown back in his face by former Manchester United manager Sir Alex Ferguson

Moyes’ show of sensitivity thrown back in his face... by Ferguson

Manchester United legend tramples on successor who resisted criticising his inheritance
Two super-sized ships have cruised into British waters, but how big can these behemoths get?

Super-sized ships: How big can they get?

Two of the largest vessels in the world cruised into UK waters last week
British doctors on brink of 'cure' for paralysis with spinal cord treatment

British doctors on brink of cure for paralysis

Sufferers can now be offered the possibility of cure thanks to a revolutionary implant of regenerative cells
Let's talk about loss

We need to talk about loss

Secrecy and silence surround stillbirth