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Holographic data storage no mirage

July 1, 2006

4 Min Read
Holographic data storage no mirage

At InPhase Technologies, the science of optics and polymer chemistry come together in 1.5 mm of photosensitive material that allows for record-breaking densities of data storage created and unlocked by lasers

On Lisa Dhar''s bookshelf in her Longmont, CO office, "Polymer Chemisty" by Heimenz and "Introduction to Organic Chemistry" by Streitweiser and Heathcock sit alongside several volumes on the science of optics. Such is life at InPhase, a spinoff from Bell Labs that has created a dual-chemistry photosensitive polymer based on polyurethane to allow holographic data storage, where instead of saving data only on the surface of a memory media, it''s collected throughout that media''s volume, using what InPhase calls its Tapestry technology (see MPW July and November 2005 for initial reports).

"It was kind of a unique environment at Bell Labs, in that we had people working from all sorts of different disciplines on the problem," says Dhar, InPhase''s VP of media. "We had material scientists, and chemical engineers and organic chemists working on the polymer, but at the same time, we would quickly get feedback from the optical engineers as to how that material was performing."

Weaving a data Tapestry

The current technology features 130-mm discs manufactured by partner Hitachi Maxell in Japan, which sit within a cartridge and are read by a drive InPhase is partnering on with other sources. The disc itself is constructed from three layers, two 1-mm amorphous polyolefin substrates, molded on standard DVD manufacturing lines, that sandwich a 1.5-mm layer, which is where information, in the form of holograms, is actually stored.

InPhase describes the middle layer as a two-chemistry photosensitive thermoset polymer, which the company has partnered with Bayer MaterialScience (Leverkusen, Germany) on for development. Made using what it calls the ZeroWave manufacturing process, the liquid thermoset is flowed between the two thermoplastic substrates and cured at room temperature, although the application of heat can accelerate the process.

The system uses two lasers to write and read a million bits of data with a single flash of light. The drive splits a laser into a reference beam and a signal beam. The signal beam carries the data and sends it through a spatial light modulator, which translates the information into binary ones and zeros expressed in light and dark pixels. Once this middle layer is exposed to the signal beam, it undergoes a chemical reaction, storing the data throughout its depth.

In the latest demonstration, InPhase stored 1.3 million bits of data per page, with the 320 data pages only spaced 0.067 degree apart. The collection of data pages, or books, can be overlapped, with three tracks of overlapping books written with a track pitch of 700 µm, greatly increasing overall data density. This fact allowed a half a terabyte (515 GB) of information to be stored on one square inch in March, breaking a record, and improving from 200 GB one year prior.

Estimating a drive''s cost at around $15,000 with individual discs coming in around $120 to $140, Liz Murphy, InPhase''s VP of marketing, says that initially potential clients with massive storage needs like government agencies and defense contractors, as well as movie studios and major broadcast networks now looking for a means to store more memory-intensive, high-definition programming will be able to justify the price given the opportunity to store such massive amounts of data on a medium that lasts 50 years.

In the near future, however, InPhase is planning a mass-market device, beginning work with a consumer electronics supplier, and expanding its Longmont operation. A handheld ROM device for video applications, the consumer device would tap the massive storage quantities the Tapestry chemistry allows, without the cost premiums associated with the commercial applications.

Material matter

Much of the storage improvement was made possible by material advances, according to Dhar. "Some kinds of polymer materials would experience deformation, dimensional change or shrinkage, when the recording laser hit the system." Through its own work, and teaming with Bayer, which became an investor as part of its open innovation model where it partners with cutting-edge firms, those challenges were overcome. "As InPhase launched [in 2000] I think they never forgot us and our chemistry strength," Bayer''s Ed Hortelano explains, "and that''s where we come to the point of them beginning to look for a very good commercial partner."

In the agreement, Bayer has secured the rights to apply this hologram technology to anything outside the field of optical data storage with InPhase as a partner. Bob Kumpf, Bayer''s VP of future business, says these potential markets include security, display, imaging, and optics, running the gamut from 3D holographic point-of-purchase displays, to heads-up dashboard displays projected onto a car''s windshield and holograms for ID cards or currency. Asked about the prospects, Kumpf quipped they were, "wonderfully huge!" before more seriously elaborating:

"The wonderful thing about really advanced markets and new product development is these things are inherently unknown. My team spends an awful lot of time trying to size potential technologies, and we do it with a combination of confidence and humility. Obviously, our involvement is an indication that it''s a market we think is substantial."

Tony Deligio [email protected]

Contact information

Bayer MaterialScience  

InPhase Technologies  

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