Holographic Memory
Holographic data storage is a potential technology in the area of high-capacity data
storage currently dominated by magnetic and conventional optical data
storage. Magnetic and optical data storage devices rely on individual
bits being stored as distinct magnetic or optical changes on the surface
of the recording medium. Holographic data storage records information
throughout the volume of the medium and is capable of recording multiple
images in the same area utilizing light at different angles.
Additionally, whereas magnetic and optical data storage records
information a bit at a time in a linear fashion, holographic storage is
capable of recording and reading millions of bits in parallel, enabling
data transfer rates greater than those attained by traditional optical storage.
Recording data
Holographic data storage contains information using an optical
interference pattern within a thick, photosensitive optical material.
Light from a single laser
beam is divided into two separate optical patterns of dark and light
pixels. By adjusting the reference beam angle, wavelength, or media
position, a multitude of holograms (theoretically, several thousand) can
be stored on a single volume.
Reading data
The stored data is read through the reproduction of the same reference beam used to create the hologram. The reference beam's light is focused on the photosensitive material, illuminating the appropriate interference pattern, the light diffracts on the interference pattern,
and projects the pattern onto a detector. The detector is capable of
reading the data in parallel, over one million bits at once, resulting
in the fast data transfer rate. Files on the holographic drive can be
accessed in less than 0.2 seconds.
Longevity
Holographic data storage can provide companies a method to preserve and archive information. The write-once, read many (WORM)
approach to data storage would ensure content security, preventing the
information from being overwritten or modified. Manufacturers
believe this technology can provide safe storage for content without
degradation for more than 50 years, far exceeding current data storage
options
.
Counterpoints to this claim are that the evolution of data reader
technology has – in the last couple of decades – changed every ten
years. If this trend continues, it therefore follows that being able to
store data for 50–100 years on one format is irrelevant, because you
would migrate the data to a new format after only ten years. However,
claimed longevity of storage has, in the past, proven to be a key
indicator of shorter-term reliability of storage media. Current optical
formats – such as CD
– have largely lived up to the original longevity claims (where
reputable media makes are used) and have proved to be more reliable
shorter-term data carriers than the floppy disk and DAT media they displaced.
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