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RENJITH PS

RENJITH PS

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Holographic memory is a technology that can store information at high density inside crystals or photopolymers.

The advantage of this type of data storage is that the volume of the recording media is used instead of just the surface .

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Technical aspects

Like other media, holographic media is divided into write once and rewritable media .

Rewritable holographic storage can be achieved via the photorefractive effect in crystals

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Mutually coherent light from two sources creates an interference pattern in the media. These two sources are called the reference beam and the signal beam

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To record on the hologram, the data in the form of electric signal is converted to optical signals by a page composer

The controller generates the address to access the desired page

This results in the exposure of a small area of the recording medium through an aperture

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The optical output signal is directed to the exposed area by the deflector

Using this beam deflecting mechanism, the light (which carries the information) and the reference beam are made to interact

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The interference pattern is thus recorded on the hologram. To record a different page, the aperture is moved and the above process is repeated.

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To retrieve the information stored in a hologram, shine the reference beam directly onto the hologram. When it reflects off the hologram, it holds the light pattern of the image stored there. Then send this reconstruction beam to a CMOS sensor to recreate the original image.

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ADVANTAGES

HVD offers several advantages over traditional storage technology. HVDs can ultimately store more than 2 terabyte (TB) of information -- that's 400 times more than a single-sided DVD and 40 times more than a current double-sided Blu-ray than a single-sided DVD and 20 times more than a current double-sided Blu-ray DVD

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HVDs also use a thicker recording layer than DVDs -- an HVD stores information in almost the entire volume of the disc, instead of just a single, thin layer.

HVDs storing holograms in overlapping patterns, while a DVD basically stores bits of information side-by-side

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The other major boost over conventional memory systems is HVD's transfer rate of up to 1 gigabyte (GB) per second -- that's 40 times faster than DVD. An HVD stores and retrieves an entire page of data, approximately 60,000 bits of information, in one pulse of light, while a DVD stores and retrieves one bit of data in one pulse of light.

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Development and marketing

At the National Association of Broadcasters 2005 (NAB) convention in Las Vegas, conducted the first public demonstrations of the world’s first prototype of a commercial storage device at the Maxell Corporation of America booth.

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The three main companies involved in developing holographic memory, Polaroid spinoff Aprilis, and Optware of Japan ,IBM

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