5093324 holographic memory

8/8/2019 5093324 Holographic Memory

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ContentsContents

1. Introduction.2. What is Holographic memory?3. What is HVD?4. Structure of HVD.5. How HVD Works?

I. Writing DataII. Reading Data

6. Advantages of HVD7. How HVD compares with otherstorage device?

8. Conclusion


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IntroductionIntroduction

As computer systems continue to become faster, they

will need a way to access larger amounts of data in

shorter periods of time.

Holographic memory is a three-dimensional data

storage system that can stored information at high

density inside the crystal or photopolymer.

Hence holographic storage system has the potential tobecame the next storage generation over conventional

storage system.


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What is Holographic Memory ?What is Holographic Memory ?

It is a memory that can store information in form ofholographic image.

It is a technique that can store information at high density

inside crystals or photopolymers.

As current storage techniques such as DVD reach the upperlimit of possible data density (due to the diffraction limited size

of the writing beams), holographic storage has the potential to

become the next generation of storage media.

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).

Rewritable holographic storage can be achieved via the photo

refractive effect in crystals.


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Holographic Versatile DiscHolographic Versatile DiscHolographic Versatile DiscHolographic Versatile Disc

Holographic Versatile Disc (HVD) is an optical disc technology still

in the research stage which would hold up to 3.9 terabyte (TB) of

information.

It employs a technique known as collinear holography, whereby two

lasers, one red and one blue-green, are collimated in a single beam.

The blue-green laser reads data encoded as laser interference fringes

from a holographic layer near the top of the disc while the red laser isused as the reference beam and to read servo information from a

regular CD-style aluminum layer near the bottom.


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Holographic Versatile DiscHolographic Versatile Disc

These discs have the capacity to hold up

to 3.9 terabyte (TB) of information,

which is approximately 6,000 times the

capacity of a CD-ROM, 830 times the

capacity of a DVD, 160 times the

capacity of single-layerBlu-ray-Discs,

and about 8 times the capacity of standard

computerhard drives as of 2007.

The HVD also has a transfer rate of1gigabyte/s


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Holographic Versatile DiscHolographic Versatile Discstructurestructure

Holographic Versatile DiscHolographic Versatile Discstructurestructure

1. Green writing/reading laser (532

nm)

2. Red positioning/addressing laser

(650 nm)

3. Hologram (data)4. Polycarbon layer

5. Photo polymeric layer (data-

containing layer)

6. Distance layers

7. Dichroic layer (reflecting green

light)

8. Aluminum reflective layer

(reflecting red light)

9. Transparent base


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The HVD System: Writing Data


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The process of writing information onto an HVD begins

with encoding the information into binary data to be

stored in the SLM. These data are turned into ones and

zeroes represented as opaque or translucent areas on a

"page" -- this page is the image that the information beamis going to pass through.


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1. Once the page of data is created, the next step is to fire a laser beam

into a beam splitter to produce two identical beams. One of the beams

is directed away from the SLM -- this beam becomes thereference

beam. The other beam is directed toward the SLM and becomes the

information beam.

2. When the information beam passes through the SLM, portions of the

light are blocked by the opaque areas of the page, and portions pass

through the translucent areas. In this way, the information beam carries

the image once it passes through the SLM.

3. When the reference beam and the information beam rejoin on the same

axis, they create a pattern of light interference -- theholography data.

This joint beam carries the interference pattern to the photopolymer

disc and stores it there as a hologram.


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The HVD System: Reading Data


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HVDHVD ComparesCompares WithWith OtherOther StorageStorage DeviceDevice

Blu-ray HD-DVD HVD

Initial cost for

recordable

disc

Approx. $18 Approx. $10 Approx. $120

Initial cost for

recorder/playe

r

Approx.

$2,000

Approx.

$2,000Approx. $3,000

Initialstoragecapacity

54 GB 30 GB 300 GB (max 3.9 TB)

Read/write

speed36.5 Mbps 36.5 Mbps 1 Gbps


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Road Map of HVD


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ConclusionConclusion

Capacity increased from 3oo Gbyte to 3.9 TB

No need to turn over the CD,DVD,HD-DVD,etc.

Three-dimensional data storage ,store information

in a smaller space and faster data transfer times .

The HVD playing device would have data rates 25

times faster than today's fastest DVD players.


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5093324 holographic memory

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