Holographic DVD adds new dimension to storage
Published: 05 Apr 2002 16:36 BST
Las Vegas is no stranger to bright lights, but next week will see an entirely new laser show as breakthrough technology shows off 3D storage for digital video.
InPhase Technologies, an offshoot of Bell Labs, will be showing the first commercial holographic video recorder at the National Association of Broadcasters (NAB) Show on 8 April. The device uses the company's Tapestry technology to hold 100GB of data on a single CD-sized write-once disc as a succession of 1.3MB holograms. That's enough for 20 full-length movies, or 30 minutes of uncompressed high-resolution video: the first product is aimed at professional video-editing, effects and archival use, with initial production at the end of 2003 and full manufacturing in 2004.
Tapestry works by splitting a laser beam into two, one of which is modulated by a megapixel array of mirrors in a TI Digital Light Processor chip with a frame of a digital video image. Recombining the two beams in a photosensitive medium results in a hologram containing the interference patterns generated; changing the parameters of the reference beam means that another hologram can be recorded in the same place in the medium as the first without mutual interference. This means a single disc can store a much higher density of information, as one location can hold multiple holograms. The hologram is read out onto a solid-state sensor chip by shining another laser with the same characteristics as the original reference beam onto the hologram: this produces the original image.
InPhase says that in addition to very high data densities -- the initial product will store twice as much as the theoretical maximum DVD can cope with -- the system will be more secure than ordinary storage as the data is distributed throughout the disc, instead of at just one layer or on the surface. The first product will have a data transfer rate of 20mbps, and the medium has a projected life of around 30 years. It uses a special polymer, developed by InPhase, that is insensitive to normal light and heat variations. The company also predicts postage-stamp formats with 2GB storage, and 20GB credit-card versions, as well as a variety of professional and home products over time.
Other companies are also working on ultra high capacity discs. Japan's Matsushita Electric Industrial has developed a two-sided optical rewritable disc that can store 100GB using violet lasers. The technology used would make DVD compatibility difficult, but Matsushita hopes the format will be used for the next generation of DVD discs.
And Constellation 3D expects its partners, including Plasmon, to ship products based on its Fluorescent Multi-layer Disc (FMD) technology, which in its first generation will allow CD-sized discs to store up to 100GB of data. Second-generation FMD technology, using blue lasers, is expected to increase this figure to one terabyte.
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