Final Sem Reporrt

7/31/2019 Final Sem Reporrt

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Danish Ahmad Khan-080011205 1

CHAPTER 1

INTRODUCTION

The Information Age has led to an explosion of information

available to users . While current storage needs are being met,

storage technologies must continue to improve in order to keep pace

with the rapidly increasing demand. A Fourth Generation Optical

Storage is an advanced optical disk that's presently in the

development stage.

A Fourth Generation Optical Storage is a volumetric approach

which , although conceived decades ago, has made recent progress

toward practicality with the appearance of lower-cost enabling

technologies .

The technology permits over 10 kilobits of data to be written and

read in parallel with a single flash.

Fourth generation storage technology, offers both high

storage density and fast readout rate.


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CHAPTER 2

HISTORY

Incomputingandoptical disc recording technologies, anoptical discis a flat,usually circular disc which encodes binary data (bits) in the form ofpits(binary

value of 0 or off, due to lack of reflection when read) and lands (binary value of1 or on, due to a reflection when read) on a special material(oftenaluminium[

citation needed]) on one of its flat surfaces. The encoding material

sits atop a thicker substrate (usuallypolycarbonate) which makes up the bulk of

the disc and forms a dust defocusing layer. The encoding pattern follows a

continuous, spiral path covering the entire disc surface and extending from theinnermost track to the outermost track. The data is stored on the disc withalaseror stamping machine, and can be accessed when the data path is

illuminated with alaser diodein anoptical disc drivewhich spins the disc at

speeds of about 200 to 4000RPMor more, depending on the drive type, disc

format, and the distance of the read head from the center of the disc (inner

tracks are read at a faster disc speed). The pits or bumps distort the reflected

laser light, hence most optical discs (except the black discs of theoriginalPlayStation video game console) characteristically haveaniridescentappearance created by the grooves of the reflective layer. The

reverse side of an optical disc usually has a printed label, generally made of

paper but sometimes printed or stamped onto the disc itself. This side of the

disc contains the actual data and is typically coated with a transparent material,usuallylacquer. Unlike the 3-inchfloppy disk, most optical discs do not have

an integrated protective casing and are therefore susceptible to data transfer

problems due to scratches, fingerprints, and other environmental problems.

Optical discs are usually between 7.6 and 30 cm (3 to 12 in) in diameter, with12 cm (4.75 in) being the most common size. A typical disc is about 1.2 mm

(0.05 in) thick, while the track pitch (distance from the center of one track to the

center of the next) is typically 1.6 m.
http://en.wikipedia.org/wiki/Computinghttp://en.wikipedia.org/wiki/Computinghttp://en.wikipedia.org/wiki/Computinghttp://en.wikipedia.org/wiki/Optical_disc_recording_technologieshttp://en.wikipedia.org/wiki/Optical_disc_recording_technologieshttp://en.wikipedia.org/wiki/Bithttp://en.wikipedia.org/wiki/Pits#Otherhttp://en.wikipedia.org/wiki/Pits#Otherhttp://en.wikipedia.org/wiki/Pits#Otherhttp://en.wikipedia.org/wiki/Aluminiumhttp://en.wikipedia.org/wiki/Wikipedia:Citation_neededhttp://en.wikipedia.org/wiki/Wikipedia:Citation_neededhttp://en.wikipedia.org/wiki/Wikipedia:Citation_neededhttp://en.wikipedia.org/wiki/Polycarbonatehttp://en.wikipedia.org/wiki/Polycarbonatehttp://en.wikipedia.org/wiki/Laserhttp://en.wikipedia.org/wiki/Laserhttp://en.wikipedia.org/wiki/Laserhttp://en.wikipedia.org/wiki/Laser_diodehttp://en.wikipedia.org/wiki/Laser_diodehttp://en.wikipedia.org/wiki/Optical_disc_drivehttp://en.wikipedia.org/wiki/Optical_disc_drivehttp://en.wikipedia.org/wiki/Optical_disc_drivehttp://en.wikipedia.org/wiki/Revolutions_per_minutehttp://en.wikipedia.org/wiki/Revolutions_per_minutehttp://en.wikipedia.org/wiki/Revolutions_per_minutehttp://en.wikipedia.org/wiki/PlayStation_(console)http://en.wikipedia.org/wiki/PlayStation_(console)http://en.wikipedia.org/wiki/Iridescencehttp://en.wikipedia.org/wiki/Iridescencehttp://en.wikipedia.org/wiki/Iridescencehttp://en.wikipedia.org/wiki/Lacquerhttp://en.wikipedia.org/wiki/Lacquerhttp://en.wikipedia.org/wiki/Floppy_diskhttp://en.wikipedia.org/wiki/Floppy_diskhttp://en.wikipedia.org/wiki/Micrometrehttp://en.wikipedia.org/wiki/Micrometrehttp://en.wikipedia.org/wiki/Floppy_diskhttp://en.wikipedia.org/wiki/Lacquerhttp://en.wikipedia.org/wiki/Iridescencehttp://en.wikipedia.org/wiki/PlayStation_(console)http://en.wikipedia.org/wiki/Revolutions_per_minutehttp://en.wikipedia.org/wiki/Optical_disc_drivehttp://en.wikipedia.org/wiki/Laser_diodehttp://en.wikipedia.org/wiki/Laserhttp://en.wikipedia.org/wiki/Polycarbonatehttp://en.wikipedia.org/wiki/Wikipedia:Citation_neededhttp://en.wikipedia.org/wiki/Aluminiumhttp://en.wikipedia.org/wiki/Pits#Otherhttp://en.wikipedia.org/wiki/Bithttp://en.wikipedia.org/wiki/Optical_disc_recording_technologieshttp://en.wikipedia.org/wiki/Computing


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CHAPTER 3

EVOLUTION OF OPTICAL DISCS

3.1) First Generation Optical Storage

The optical disc was invented in 1958.

Initially, optical discs were used to store music and computer software.


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The Laser disc format stored analog video signals for the distribution of home

video.

Other first-generation disc formats were designed only to store digital data and

were not initially capable of use as a digital video medium.

Most first-generation disc devices had an infrared laser reading head.

The minimum size of the laser spot is proportional to its wavelength, thus

wavelength is a limiting factor against great information density, too little data

can be stored so. The infrared range is beyond the long-wavelength end of the

visible light spectrum, so, supports less density than any visible light colour.

One example of high-density data storage capacity, achieved with an infraredlaser, is 700 MB of net user data for a 12 cm compact disc.


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3.2) Second Generation Optical Storage

Second-generation optical discs were for storing great amounts of data,

including broadcast-quality digital video.

Discs usually are read with a visible-light laser (usually red) the shorter

wavelength and greater numerical aperture allow a narrower light beam,

permitting smaller pits and lands in the disc.

In the DVD format, this allows 4.7 GB storage on a standard 12 cm, single-sided,

single-layer disc; alternatively, smaller media, such as the Mini Disc can have capacity

comparable to that of the larger, standard compact 12 cm disc.


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3.3)Third Generation Optical Storage

Third-generation optical discs are meant fordistributing high-definition video and support greater data

storage capacities.

high-definition video and greater data storageaccomplished with short-wavelength visible-light lasers and

greater numerical apertures.

The Blu-ray disc uses blue-violet lasers and focusing opticsof greater aperture, for use with discs with smaller pits and

lands, thereby greater data storage capacity per layer.

The effective multimedia presentation capacity is improvedwith enhanced video data compression codecs .

3.3.1) Blu-ray Discs

The first Blu-ray Disc prototypes were unveiled in October 2000, and the first

prototype player was released in April 2003 in Japan.

It was officially released in June 2006.

Blu-ray Disc (official abbreviation BD) is an optical disc storage medium

designed to supersede the DVD format.

The disc diameter is 120 mm and disc thickness 1.2 mm plastic optical disc, the

same size as DVDs and CDs.

Blu-ray Discs contain 25 GB per layer, with dual layer discs (50 GB) being the

norm for feature-length video discs. Triple layer discs (100 GB) and quadruple

layers (128 GB) are available for BD-XL Blu-ray re-writer drives.


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The nameBlu-ray Disc refers to the blue laser used to read the disc, which

allows information to be stored at a greater density than is possible with the

longer-wavelength red laser used for DVDs.

"Blu-ray Disc recordable" refers to two optical disc formats that can be recorded

with an optical disc recorder.

BD-Rs can be written to once, whereas BD-REs can be erased and re-recorded

multiple times.

The current practical maximum speed for Blu-ray Discs is about 12. Higher

speeds of rotation (10,000+ rpm) cause too much wobble for the discs to be read

properly.

September 2007, BD-RE is also available in the smaller 8 cm Mini Blu-ray

Disc size


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CHAPTER 4

FOURTH GENERATIONOPTICAL DISC

The following formats go beyond the current third-generation discs and have the

potential to hold more than one terabyte (1 TB) of data:

4.1) Holographic Versatile Disc

Although holography was conceived in the late 1940s, it was not considered apotential

storage technology until the development of the laser in the 1960s. The resulting

rapid

development of holography for displaying 3-D images led researchers to realize

that holograms could also store data at a volumetric density of as much as 1/ A3

where A, is the wave-length of the light beam used.

Since each data page is retrieved by an array of photo detectors in parallel, rather thanbit-by-bit, the holographic scheme promises fast readout rates as well as high density.

The particular technology used in the production of HVD is known as collinearholography. This technology involves the collimating of two lasers, of which

one is blue-green and the other red, to form a single beam.

The blue-green laser reads the data that is encoded in the form of laserinterference fringes emitted from the holographic layer that is on the top.

The red laser on the other hand acts as a reference beam. Holographic data storage works on the principle of holography. In holographic

data storage an entire page of information is stored at once as an optical

interference pattern within a thick, photosensitive optical material.


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Holographic Versatile Disc can store data upto several TB. Current optical storage saves one bit per pulse, and the HVD alliance hopes to

improve this efficiency with capabilities of around 60,000 bits per pulse in an

inverted, truncated cone shape that has a 200 m diameter at the bottom and a

500 m diameter at the top. High densities are possible by moving these closeron the tracks: 100 GB at 18 m separation, 200 GB at 13m, 500 GB at 8m,

and most demonstrated of 5 TB for 3 m on a 10 cm disc.

The system uses a green laser, with an output power of 1 watt which is highpower for a consumer device laser. Possible solutions include improving the

sensitivity of the polymer used, or developing and commoditizing a laser

capable of higher power output while being suitable for a consumer unit

4.1.1) ARCHITECTURE OF HOLOGRAPHHICVERSATILE DISC

1. Green writing/reading laser (532 nm) 2. Red positioning/addressing laser (650 nm) 3. Hologram (data)(shown here as brown)

4. Polycarbonate layer 5. Photo polymeric layer (data-containing layer) 6. Distance layers 7. Dichroic layer (reflecting green light) 8. Aluminium reflective layer (reflecting red light) 9. Transparent base P. Pit pattern
http://en.wikipedia.org/wiki/Laserhttp://en.wikipedia.org/wiki/Watthttp://en.wikipedia.org/wiki/Polymerhttp://en.wikipedia.org/wiki/Polymerhttp://en.wikipedia.org/wiki/Watthttp://en.wikipedia.org/wiki/Laser


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4.2) LS-R

LAYER SELECTION TYPE RECORDABLE DISC:-

LS-R, or the Layer-Selection-Type Recordable Optical Disk, is the term coinedby Hitachi in 2003.

This optical disc technology allows much larger data storage densitiesthan DVD, HD DVD or Blu-ray Disc, by allowing the use of a large number of

data layers in a single disc.

In LS-R, only the layer of interest generates a reflection, meaning that a verylarge number of layers can theoretically be stacked in the same disc

This reflection phenomenon from a particular layer is accomplished by an

electronic "selection" mechanism.

Each data layer is coated with electrodes and only the electrodes associated withthe layer of interest are activated.

Activation changes the "selected" data layer from being transparent to beingreflective or opaque, thus it can be addressed.


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4.2.1)Layer Structure(LS-R)

4.2.2) TECHNOLOGY

In the Hitachi implementation, LS-R technology utilizes an electrochromic film.

Example:-

Tungsten oxide or an organic material to accomplish the optical change.

A two-layer feasibility prototype has been demonstrated, and it was estimatedthat a 20-layer CD-sized disc could provide 1 terabyte of data capacity.

Electrical activation of layers has been achieved with transparent ITO(Indiumtin oxide) electrodes.


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4.3) PROTIEN COATED DISC

Protein-Coated Disc (PCD) is a theoretical optical disc technology currentlybeing developed by Professor V.R Gopalkrishnan, formerly of Harvard Medical

School and Florida International University.

PCD would greatly increase storage over Holographic Versatile Disc opticaldisc systems.

It involves coating a normal DVD with a special light-sensitive protein madefrom a genetically altered microbe.

It would in principle allow storage of up to 50 Terabytes on one disc.

The technology uses the photosynthetic pigment bacteriorhodopsin created frombacteria.

4.3.1)TECHNOLOGY USED

The information in such discs would be highly dense. Due to being stored in proteins that are only a few nanometres across. A method to address individual protein molecules to read and write information

to and from them would have to be developed in order to achieve the theoretical

50 TB capacity.

capacity would probably be limited by the size that addressing light can befocused to, so a DVD-sized disc might be able to hold ~50 GB.

rotating about an axis point, to closely replicate head movements without being

attached to the head.


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CHAPTER 5

ADVANTAGE OF OPTICAL DISCSA direct access storage device that is written and read by light. The most common optical discs in use

are CDs and DVDs. As removable media, optical discs have advantages over the older removable

magnetic disk cartridges. They weigh less, have higher capacities and are not subject to head crashes

or corruption from stray magnetic fields. They also have a 30-year life and are less vulnerable to

extremes of hot and cold. However, flash drives and external hard disks that plug into the USB port

have given optical discs a run for their money as a transportable storage medium. Following are the

major types.

Read-Only (Factory Pressed)

Read-only discs are pressed from a master at the time of manufacture and cannot be erased. They

include the music CD, CD-ROM, DVD-ROM, DVD-Video and BD-ROM (Blu-ray).

Write-Once (Burnable)

Write-once discs are recorded in the user's environment but cannot be erased. They include the CD-R,

DVD-R, DVD+R, BD-R (Blu-ray), WORM discs, as well as magneto-optic (MO) discs in WORM mode.

Rewritable (Phase Change and Magneto Optic)

Rewritable discs can be written and re-written numerous times. Employing phase change technology,

consumer-oriented products include CD-RW, DVD-RAM, DVD-RW, DVD+RW and BD-RE (Blu-ray)(seephase change disc).

Used in corporate optical disc libraries that hold multiple cartridges, magneto-optic (MO) disks are

extremely robust (seemagneto-optic disk). SeeDVD,holographic storage,ISO 13346,multilevel optical

discandlegality of optical storage.

Writability Optical Disc Types

Read only CD, CD-ROM

DVD-ROM, DVD-Video

BD-ROM

Write once CR-R

DVD-R, DVD+RBD-R, WORM

Rewritable CD-RW

DVD-RAM, DVD-RW, DVD+RW

BD-RE, magneto-optic (MO)
http://www.answers.com/topic/phase-change-dischttp://www.answers.com/topic/phase-change-dischttp://www.answers.com/topic/phase-change-dischttp://www.answers.com/topic/magneto-optic-disk-technologyhttp://www.answers.com/topic/magneto-optic-disk-technologyhttp://www.answers.com/topic/magneto-optic-disk-technologyhttp://www.answers.com/topic/dvdhttp://www.answers.com/topic/dvdhttp://www.answers.com/topic/dvdhttp://www.answers.com/topic/holographic-data-storagehttp://www.answers.com/topic/holographic-data-storagehttp://www.answers.com/topic/holographic-data-storagehttp://www.answers.com/topic/iso-13346-technologyhttp://www.answers.com/topic/iso-13346-technologyhttp://www.answers.com/topic/iso-13346-technologyhttp://www.answers.com/topic/multilevel-optical-dischttp://www.answers.com/topic/multilevel-optical-dischttp://www.answers.com/topic/multilevel-optical-dischttp://www.answers.com/topic/multilevel-optical-dischttp://www.answers.com/topic/optical-storagehttp://www.answers.com/topic/optical-storagehttp://www.answers.com/topic/optical-storagehttp://www.answers.com/topic/optical-storagehttp://www.answers.com/topic/multilevel-optical-dischttp://www.answers.com/topic/multilevel-optical-dischttp://www.answers.com/topic/iso-13346-technologyhttp://www.answers.com/topic/holographic-data-storagehttp://www.answers.com/topic/dvdhttp://www.answers.com/topic/magneto-optic-disk-technologyhttp://www.answers.com/topic/phase-change-disc


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