The road to Holography

There is much talk of the new blue laser formats being “next-generation” products. But, if we are to move into the era of Home Media Servers, downloadable HD video and digital home movies, we are going to need terabytes of backup storage, not gigabytes, argues BOB AUGER, from consultancy Newmérique.

In 1995, when Toshiba/Warner and Sony/Philips patched up their differences to create the DVD Consortium (later the DVD Forum), the playing time was a major requirement in drawing up the DVD specification. Laserdisc and CD-i formats held an hour or less of full motion video, convincing the studios that any new standard must deliver a complete film without the need to change discs.

Once playback of titles such as Gone with the Wind (233 minutes long) could be accommodated on a dual-layer single-sided DVD, the demise of other videodiscs was assured. The keyword is, of course, playback. Disc-based systems at this time did not offered any satisfactory recording ability, though it could be argued that Edison and his wax cylinder started the industry off on the right path.

From the time that the Magnetophone was shown to Berlin journalists in June 1941 until the arrival of the CD-R in 1988, magnetic media held sway as the optimum recording medium. Although open reel systems failed to find favour with the consumer, the idea of putting two reels in a single box called a cassette was a breakthrough. Philips and Grundig introduced incompatible audio cassettes in the mid- sixties and both courted Sony with a view to establishing a world standard. Eventually, a deal was done to use the Philips Compact Cassette in the Sony Walkman and a legend was born.

It was a short step conceptually (though a technical achievement) to video cassette recorders and the eventual emergence of VHS as the dominant format. Video Home Entertainment had arrived – and it was tape-based.

If we only had to consider the entertainment industry, it would be possible to conclude “Magnetic media has had its day and now everything is moving to disc-based and solid state storage.” But life is not so simple.

While VHS has started its steep decline and audio tape is history, spinning magnetic discs have been refined and improved. The computer industry has been driven by different imperatives from packaged media retailing, leading to “byte inflation” that has taken even a home computer into the realm of terabyte storage.

In much the same way that household waste piles up in wheelie bins, mp3 music, digital photographs and home movies accumulate in the confines of your PC. Eventually the dreaded message appears “disk in destination drive is full”, at which point we reach for the CD-R, realise it is too small, insert a DVD and discover that 4.7GB goes nowhere, buy a dual- layer burner and finally manage to squeeze the winter holiday videos onto 8.5GB media.

It is at about this time that the consumer realises that ‘convergence’ has not gone quite as far as it might have. Packaged media storage requirements have been driven by the ability to fit a feature film onto a single disc side but computer storage requirements have become a hundred times greater.

Blu-ray and HD DVD battle over the difference between 30 and 50 Gbyte capacity. Yet, even a basic PC may have an 80GByte hard drive and the relatively modest computer on which this was typed has 500GB on-line. The idea of a weekly backup onto a dozen or more Blu-ray discs is not appealing.

There is much talk of the new blue formats being “next-generation products”. In the context of high definition replacements for existing DVDs, they are, but if we are to move into the era of Home Media Servers, downloadable HD video and digital home movies, we are going to need terabytes of backup storage, not gigabytes.

Holographic solutions

Led by Optware in Japan, companies large and small are betting the family farm that what we will need in the future is the HVD or Holographic Versatile Disc. With the same form factor as existing consumer optical discs like CDs and DVDs (12cm in diameter and 1.2 mm thick) the HVD could be the much sought-after “Next Generation” solution for home entertainment storage.

At the time of writing (April) the HVD Alliance is planning to demonstrate a 3.9 Terabyte holographic storage system at Media-Tech Expo in Frankfurt at the end of May 2006. Now that is Next Generation storage – it will be a while before most home users can fill nearly 4,000 Gigabytes of space.

Meantime InPhase Technologies, in Longmont, California, has been concentrating on archive applications, announcing at CES in January 2006 that the company is shipping the Tapestry H-ROM holographic system, which will record 300 GB of data onto a 13 cm disc at up to 20 MB per second. Transfer rates of this order will be required for HDTV and enterprise computer applications.

How will holographic storage affect us?

Holography was invented, almost by accident, by the Hungarian scientist Denis Gabor in 1947. He was trying to photograph an atom but ended up with a three-dimensional photograph and was later awarded the Nobel Prize. In 1963, using the recently-invented laser, two scientists at the University of Michigan produced a 3-D image of a model train and uncorked a flood of interest in holography that has continued to the present day.

For many people, holography is about 3-D photography, but RCA have more strings to their bow than 45 rpm vinyl records and 1977 saw the company applying for patents to cover ‘holographic storage using photo polymers’ and the seed of high density data storage was planted.

When Hideyoshi Horimai, CTO and founder of Optware Corporation, decided to combine pre-formatted servo information with holographic data storage on a rotating 12cm disc, the possibilities for commercial applications began to grow. The company was incorporated in 1999 and demonstrated the first film playing back from a holographic disc in 2004.

Optware’s Collinear holographic recording technique utilises a dichroic mirror layer between the pre-formatted address pits and the recording layer, which prevents crosstalk between the servo information and the recording data. A conventional 0.6mm substrate and data layer means that the 1.2mm HVD disc is physically compatible with conventional CD, DVD and HD DVD construction.

A red 650nm laser is used to read the servo information. While the initial release will use a green laser of 732nm wavelength, Optware is considering using a 405nm blue-violet laser for data read/write and a lens numerical aperture of 0.65. These proposed standards parallel those set for HD DVD, which raises the possibility of a dual HD DVD/HVD drive, though the method of operation is completely different.
What separates the technology of conventional CD/DVD discs and the HVD format is essentially the delivery of data from disc to decoder.

All optical disc systems to date have delivered data serially from the data layer, in which each pit represents a zero or a one. This data can be reconstructed into the bits of data that made up the original digital information.

The information progressively fills a buffer, from which the information can be read every time a page has been loaded. The faster the disc spins, the more pulses can be retrieved each second and the sooner the buffer can be read, hence the arrival of 2X, 4X and 8X drives. However, we are approaching the limits of spin speed and already there are stories in the media of discs disintegrating within the drive.

HVD delivers data on a page basis. Each pulse delivers not one but sixty thousand bits of information into the buffer. Data is delivered in a parallel manner, with all bits arriving at the same time, in line with the parallel processing that takes place in a modern computer.

Over ten thousand pages of data can be written each second and around 270 Mbps can be delivered to the host system, compared with 38Mbps from blue laser formats and 10Mbps on standard DVD. One of the many additional advantages of holography is that the HVD disc is inherently secure, with an estimated 210,000 keys per page and the possibility of changing the key with each page read.

Not surprisingly, Optware has attracted investment and partnerships from around the world, including an EU project led by Thomson with MPO, Toptica Photonics AG, RWTH Aachen and Budapest University among others contributing.

The HVD Alliance was announced in Japan in February 2005, with six founding members including Optware Corporation; CMC Magnetics Corporation; Fuji Photo Film; Nippon Paint; Pulstec Industrial; and the Toagosei Company. The group now has ten members and plans to accelerate the development of HVD and to promote the technology. Development agreements with Sony and investment from Toshiba in June 2005 are further milestones on the road to HVD success.

Yasuhide Kageyama, Business Development & Marketing Manager for the Optware Corporation and spokesman for the HVD Alliance Promotions Committee confirms that the commercial launch of HVD is planned for 2006 but the focus will be on HVD as an archive format.

“The holographic recording layer is light sensitive material and needs to be kept in a lightproof cartridge,” he explains “The cost of a single HVD disc will consequently be higher than that of recordable CD, DVD or HD DVD but of course it will store many times more data.”
In 2006 Optware will launch Magnum, an archival data-storage system with 200 GB capacity and a recording pitch of 13 microns, increasing over time to a maximum of 3.9TB and a 3 micron pitch.

However, Kageyama makes clear that this increase in capacity will not directly increase the price, as it is related only to a reduction in the recording pitch and backward compatibility will be built-in. “The cost per Gigabyte will be competitive and will fall over time. We are expecting 500GB discs to be delivered within three years.”

With an eye to the format battles happening elsewhere in the packaged media world, the HVD Alliance is pursuing standardisation with ECMA in Geneva.
HVD is the only holographic disc that has been proposed for standardisation and the process is on track. Yoshio Aoki, CEO of Optware Corp. of America, is ex-Sony and holds patents relating to the cover layer of the Blu-ray format. He joined the company in 2002 with a brief to focus on standardisation and alliances, a task that he has accomplished with notable success. HVD is an open standard.

Although there are other companies involved in holographic disc research, a future ‘holographic format war’ seems unlikely to affect consumers. InPhase, with corporate partners Hitachi Maxell, Bayer Material Science and ALPS IT Fund is concentrating on data storage applications with its H-ROM format and Tapestry media. This technology will be incorporated into low-cost readers that will be licensed to consumer electronics companies in the near future.

InPhase CTO and co-founder, Kevin Curtis, says “The InPhase legacy of persistent invention has produced numerous breakthroughs on the road to commercial holographic recording systems.”

In a CES 2006 press release, Lisa Dhar, VP of Media Development at InPhase Technologies adds “Today’s CDs and DVDs are based on red laser technology and Tapestry HDS4000 media, which is sensitive to 680nm wavelengths, enables the development of low-cost consumer holographic devices based on these red lasers. This will usher in an era of devices that provide the performance and capacity of commercial products at consumer prices.” The media product family from In-Phase includes green laser HDS3000 media, and blue laser HDS5000 media.

What successor to DVD?

This brings us back to Blu-ray, HD DVD and which should be crowned as the HDTV successor to DVD? In fact, the maximum playing time of both discs is matched to the requirements of the film industry and the running time of cinema releases. Both formats are able to deliver the longest features within their existing specification, perfect for the needs of packaged media.

When blue laser recordable versions start to boast about their storage capacity however, questions need to be asked. At Mediatech in 2005, a Frankfurt banker announced that he viewed HD DVD as “an interim solution,” with Blu-ray as “the storage medium of th future.” In truth, neither disc comes near the needs of next-generation applications when compared to the promise of holographic formats.

In the future world of Home Media Networks, recordable storage will need to offer several multiples of the running time of a single title. For Blu-ray and HD DVD, that multiple is one – one disc, one film – which underlines the fact that these discs may be ideally matched to Video Home Entertainment but they are not the ultimate answer for storage, backup and archiving.

Distributors and retailers prefer to sell several ‘short’ discs rather than one tightly-packed version, as the lack of enthusiasm for DVD-18 demonstrates. The public perception is that a two- or three-disc boxed set of DVD-5s is better value than a single DVD-9, even if the total running time is the same.

Feature films are unlikely to increase in length significantly in the foreseeable future, however, Home Video Server storage requirements are set to expand dramatically with the arrival of HD. The HVD disc can currently store a multiple of at least four high definition movies, a capacity that will grow to ten by 2008 and promises to hold the equivalent of around eighty titles on a single disc by the end of the decade.

For the moment, holographic disc proponents are happy to let conventional formats divide up the high definition Home Video Entertainment market while they concentrate on storage arrays for Electronic Cinema, simultaneous IP Multicast streams and HD record and playback for professional applications.

Both Toshiba and Sony have taken a position in the Optware holographic camp, Hitachi Maxell is a partner with InPhase. Although the respective investments are small at the moment, these and other companies are well placed to commercialise holographic storage technologies.

There are probably three steps to packaged media heaven, starting with DVD, passing through Blu-ray and/or HD DVD and culminating in holographic discs. When you have a product that is as future-proof as HVD, you can afford to wait while format wars play themselves out.
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