2. Computer Storage or Mass Storage is generally defined
as a means of preserving computer generated
information for subsequent use or retrieval.
Computer Storage
3. Random Access
Serial Access
?
What will be the next logical step in computer storage ?
Parallel Access
Parallel Access Is The Ability To
Put Information In Any Form,
And Take It Out At The Same
Rate.
In Other Technologies, We Get
One Bit Stream At A Time.
Higher Bandwidth Is The Result.
4. • Holographic memory is a three-dimensional data
storage system that can store information at high
density inside the crystal or photopolymer.
• It is a memory that can store information in the form
of holographic image (hologram).
• Like other media, holographic media is divided into
write once (where the storage medium undergoes
some irreversible change), and rewritable media
(where the change is reversible).
What is Holographic Memory?
5. Working Principle
• In holographic data storage, an entire page of information is
stored at once as an optical interference pattern within a
thick, photosensitive optical material.
• This is done by intersecting two coherent laser beams within
the storage material.
• The first, called the object beam, contains the information to
be stored; the second, called the reference beam, is a
simple light wave.
• When the two combine in an optical storage medium, they
change the chemical or physical construction of that
medium and so store the data.
• If the storage medium is then illuminated with the reference
beam again, the object data beam is produced.
6. Spatial Light Modulator
• SLM is a 1024 * 1024 array of light or dark
squares.
• This array represents the data to be stored,
and is usually implemented by a set of
pixels on an LCD.
• An SLM can usually be refreshed at rates
of about 1000 frames per second.
7. Laser
• Blue-green argon laser which is split into two beams, a
reference beam and an object beam.
• The interference pattern created by these two beams forms
the hologram.
8. Spatial Light Modulator
• SLM is a 1024 * 1024 array of light or dark
squares.
• This array represents the data to be stored, and
is usually implemented by a set of pixels on an
LCD.
• An SLM can usually be refreshed at rates of
about 1000 frames per second.
9. Multiplexing Agent
• It is used to allow the laser beam to access different
pages in the hologram.
• Two types of multiplexing, shift multiplexing and angular
multiplexing
• Shift Multiplexing uses a rotating disk to vary the angle
of the laser beam, and so access a different view of the
hologram.
• Angular multiplexing uses mirrors to change the angle at
which the laser strikes the crystal.
11. Charge Coupled Device (CCD)
• CCD is an array of sensors which corresponds to
the pixels on the SLM.
• The CCD is used to read the interference pattern
from the reference beam, and so read the
information from the hologram.
• The matrix construction of the CCD allows it to
read all 1Mb of the data at once.
• Typical CCD dimensions are one square
centimeter, and typical access rates are 1000
frames / second, or 1 Gigabit / second.
14. • HVD is an advanced optical disk that’s presently in the
development stage.
• It can transfer data at the rate of 1 Gigabit per second.
• The technology permits over 10 kilobits of data to be
written and read in parallel with a single flash.
• The disk will store 1 terabyte (TB) of data on a single
optical disk.
Holographic Versatile Disc
15.
16. DVD BLU-RAY HVD
Capacity 9.4 GB 50GB (max 3.9 TB)
Laser wave
length
650 nm 405 nm 407 nm
Disc diameter 120 mm 120 mm 120 mm
Read/write
speed
11.08 Mbps 36 Mbps 1 Gbps
Comparison With Other Storage DevicesComparison With Other Storage Devices
17. •Entire page of data can be retrieved quickly and at one time.
• Offers storage of 1 TB (up to 3.9 TB) of data.
• Its transfer rate is so high that a person can easily load the
required data.
• Resistant to damage.
ADVANTAGE
18. •Very high cost.
• Needs separate instrument for its operation.
DISADVANTAGE
19. • Holographic Data Storage disk will be the next
technological revolution.
• The page access of data that holographic memory
creates will provide a window into next generation
computing by adding another dimension to stored
data.
• The large cost of high-tech optical equipment would make
small-scale systems implemented with holographic
memory impractical.
Conclusion
