Blu‐ray Disc-2

7/28/2019 Bluray Disc-2

1/37

ABSTRACT

Optical discs share a major part among the secondary storage devices. Blu-ray disc is a next generation

optical disc format. The technology utilizes a blue laser diode operating at a wavelength of 405nm to read

and write data. Because of the blue laser it can store enormous amount of data than was ever possible.

Data is stored on a BD in the form of tiny ridges on the surface of an opaque 1.1mm thick substrate. This

lies beneath a transparent .1mm protective layer. With the help of Blu-ray recording devices it is possible to

record upto 2.5 hrs of very high quality audio and video on a single BD.

Blu-ray also promises some added security, making ways for copyright protections. BD can have a unique

ID written on them to have copyright protection inside the recorded streams.

Blu-ray Disc takes the DVD technology one step further just by using a laser with a nice colour.

D e p a r t m e n t o f E l e c t r o n i c s & C o m m u n i c a t i o n E n g i n e e r i n g

G E E T A N J A L I I N S T I T U T E O F T E C H N I C A L S T U D I E S

UDAIPUR, RAJASTHAN


2/37

INDEX

INTRODUCTION..

HISTORY OF BLU-RAY DISC..

FIRST GENERATION.

SECOND GENERATION.

THIRD GENERATION

GLOSSARY OF TERMS

LAYER

SDTV.

NUMERICAL APERTURE

BLUE LASER

OPTICAL DATA STORAGE FOR DIGITAL VIDEO

INTRODUCTION

PARAMETERS FOR HD VIDEO STORAGE WITH OPTICAL

DISCS.

OPTICAL PARA METER

DISK STRUCTURE PARAMETERS

DATA MANAGEMENT PARAMETERS.

DIFFERENT FORMATS OF BD

TWO VERSIONS OF RECORDING

ONE TIME RECORDING..

RECORD MANY TIMES.

BLU-RAY DISC STRUCTURE.

BLU-RAY DISC CHARACTERISTICS..

LARGE RECORDING CAPACITY

HIGH SPEED

RESISTANCE TO SCRATCHES

AND FINGERPRINTS..D e p a r t m e n t o f E l e c t r o n i c s & C o m m u n i c a t i o n E n g i n e e r i n g


UDAIPUR, RAJASTHAN


3/37

CHARACTERISTICS OF IDEAL COMMUNICATION..

HOW DOES BLU-RAY DISC WORK?

COMPARISONS.

BLU-RAY DISC AND HD-DVD

ADVANTAGES OF BD.

APPLICATIONS

HIGH DEFINITION TELEPHONE RECORDING

HIGH DEFINITION VIDEO DISTRIBUTION

HIGH DEFINITION CAMCORDER ARCHIVING

MASS DATA STORAGE.

DIGITAL ASSET MANAGEMENT AND PROFESSIONAL

STORAGE

REQUIREMENTS

CHALLENGES.

FUTURE DEVELOPMENTS.

CONCLUSION.

REFERENCES



UDAIPUR, RAJASTHAN


4/37

Introduction

Tokyo Japan, February 19, 2002: Nine leading companies announced that they have jointly established

the basic specifications for a next generation large capacity optical disc video recording format called

"Blu-ray Disc". The Blu-ray Disc enables the recording, rewriting and play back of up to 27

gigabytes (GB) of data on a single sided single layer 12cm CD/DVD size disc using a 405nm blue-

violet laser.

By employing a short wavelength blue violet laser, the Blu-ray Disc successfully minimizes its beam

spot size by making the numerical aperture (NA) on a field lens that converges the laser 0.85. In

addition, by using a disc structure with a 0.1mm optical transmittance protection layer, the Blu-ray

Disc diminishes aberration caused by disc tilt. This also allows for disc better readout and an

increased recording density. The Blu-ray Disc's tracking pitch is reduced to 0.32um, almost half of

that of a regular DVD, achieving up to 27 GB high-density recording on a single sided disc.

Because the Blu-ray Disc utilizes global standard "MPEG-2 Transport Stream" compression technology

highly compatible with digital broadcasting for video recording, a wide range of content can be recorded. It

is possible for the Blu-ray Disc to record digital high definition broadcasting while maintaining high quality

and other data simultaneously with video data if they are received together. In addition, the adoption of a

unique ID written on a Blu-ray Disc realizes high quality copyright protection functions.

The Blu-ray Disc is a technology platform that can store sound and video while maintaining high qualityand also access the stored content in an easy-to-use way. This will be important in the coming broadband

era as content distribution becomes increasingly diversified. The nine companies involved in the

announcement will respectively develop products that take full advantage of Blu-ray Disc's large capacity

and high-speed data transfer rate. They are also aiming to further enhance the appeal of the new format

through developing a larger capacity, such as over 30GB on a single sided single layer disc and over 50GB

on a single sided double layer disc. Adoption of the Blu-ray Disc in a variety of applications including PC

data storage and high definition video software is being considered.



UDAIPUR, RAJASTHAN


5/37

Concept of the format establishment:

To realize the large capacity with 12cm disc

- More than 2-hour high definition video recording

- High capacity of more than 4-hour recording by double layer technology.

To cope with digital broadcasting

- High compatibility with digital broadcasting

- To prevent illegitimate duplication of contents

To enhance the Blu-ray Disc world

- Adoption of the Blu-ray Disc in variety of media and applications

Main Features of physical format:

Large recording capacity up to 27GB

By adopting a 405nm blue-violet semiconductor laser, with a 0.85NA field lens and a 0.1mm optical

transmittance protection disc layer structure, it can record up to 27GB video data on a single sided 12cm

phase change disc. It can record over 2 hours of digital high definition video and more than 13 hours of

standard TV broadcasting (VHS/standard definition picture quality, 3.8Mbps)

Easy to use disc cartridge:

An easy to use optical disc cartridge protects the optical disc's recording and playback phase from dust and

fingerprints

High-speed data transfer rate 36Mbps:

It is possible for the Blu-ray Disc to record digital high definition broadcasts or high definition images from

a digital video camera while maintaining the original picture quality. In addition, by fully utilizing an

optical disc's random accessing functions, it is possible to easily edit video data captured on a video camera

or play back pre-recorded video on the disc while simultaneously recording images being broadcast on TV .

Recording format:

Like the DVD, the Blu-ray disc uses phase change recording. This must be good news for those who plan to

make the new format compatible with its wildly popular predecessor. This recording format will also makes

a two-sided disc easily realizable because both writing and reading can be executed by a single pickup.

Multiplexing:

Blu-ray disc utilizes global standards like MPEG-2 Transport Stream compression technology for

video and audio multiplexing. This makes it possible for a Blu-ray Disc to record high definition

broadcasting and other data simultaneously with video data if they are received together. Data



UDAIPUR, RAJASTHAN


6/37

captured on a video camera while recording images being broadcast on TV can also be edited

simultaneously.

Main Features Of Logical format :

Highly compatible with digital broadcasting :

MPEG2 transport stream compression technology for video recording can record digital broadcasting

including HDTV while maintaining its original picture quality.

Best data structure for disc recording

Achieving improvement of searching, easy editing functions and play a list playback functions by adapting

logical data structure making the best use of random accessing.

File system for HDTV real time recording

Adapting the file system which can achieve high bit rate recording and playback of HDTV and best use of

disc space



UDAIPUR, RAJASTHAN


7/37

History of Bluray Disc

First Generation

When the CD was introduced in the early 80s, it meant an enormous leap from traditional media. Not

only did it offer a significant improvement in audio quality, its primary application, but its 650 MB

storage capacity also meant a giant leap in data storage and retrieval. For the first time, there was a

universal standard for prerecorded, recordable and rewritable media, offering the best quality and

features consumers could wish for themselves, at very low costs.

Second Generation

Although the CD was a very useful medium for the recording and distribution of audio and some modest

dataapplications, demand for a new medium offering higher storage capacities rose in the 90s. These

demands lead to the evolution of the DVD specification and a five to ten fold increase in capacity. This

enabled high quality, standard definition video distribution and recording. Furthermore, the

increased capacity accommodated more demanding data applications. At the same time, the DVD

spec used the same form factor as the CD, allowing for seamless migration to the next generation

format and offering full backwards compatibility.

Third Generation

Now High Definition video is demanding a new solution. History proved that a significant five to ten

time increase in storage capacity and the ability to play previous generation formats are key elements

for a new format to succeed. This new format has arrived with the advent of Bluray Disc, the only

format that offers a considerable increase in storage capacity with its 25 to 50 GB data capacity. This

allows for the next big application of optical media: the distribution and recording of High Definition

video in the highest possible quality. In fact, no other proposed format can offer the data capacity of

Bluray Disc, and no other format will allow for the same high video quality and Interactive features

to create the ultimate user experience. As with DVD, the Blu-ray Disc format is based on the same,

bare disc physical form factor, allowing for compatibility with CD and DVD. The Blu ray Disc

specification was officially announced in February 2002. Bluray Disc recorders were first launched in

Japan in 2003.

1982 First working CD player developed by Philips. Philips and Sony developed CD standard 12cm

disk, 74 minutes on a single spiral

1983 First CD players sold

1985 CDROM introduced not popular at first. More powerful PCs lead

to demand for multimedia, image processing and larger applications. Growth in sales brings prices down.

1990s CDR and CDRW introduced big success.



UDAIPUR, RAJASTHAN


8/37

1996 DVD introduced

1999 DVD becomes mainstream

2003 BD introduce

GLOSSARY OF TERMS

Layer

In Bluray Disc, data is recorded on a single side of the disc. However, a disc can store two data layers,

both at the same side. The readout or recording laser of the Bluray Disc device will first read from or

record to one layer, and then refocuses on the second layer. All this is done automatically without

any user interference. A double layer Bluray Disc can store upto 50 GB of data.

SDTV

It stands for Standard Definition Television. Generic term used for conventional television sets,

based on the NTSC or PAL standards. SD television consists of 480 to 570 visible lines.

Numerical Aperture and Resolution

The numerical aperture of a microscope objective is a measure of its ability to gather light and resolve

fine specimen detail at a fixed object distance.



UDAIPUR, RAJASTHAN


9/37

Imageforming light waves pass through the specimen and enter the objective in an inverted cone as

illustrated in Figure 1. A longitudinal slice of this cones of light shows the angular aperture, a value

that is determined by the focal length of the objective. The angle is onehalf the angular aperture

(A) and is related to the numerical aperture through the following equation:

Numerical Aperture (NA) = n (sin )

Where n is the refractive index of the imaging medium between the front lens of the objective and the

specimen cover glass, a value that ranges from 1.00 for air to 1.51 for specialized immersion oils.

Many authors substitute the variable for in the numerical aperture equation. From this equation

it is obvious that when the imaging medium is air (with a refractive index, n = 1.0), then the numerical

aperture is dependent only upon the angle whose maximum value is 90. The sin of the angle ,

therefore, has a maximum value of 1.0 (sin90 = 1), which is the theoretical maximum numerical

aperture of a lens operating with air as the imaging medium (using dry microscope objectives).

THE BLUE LASER

The laser used with the Bluray disc has a wavelength of 405nm.Though the red and the green lasers were

discovered much earlier, it was only in 1996 that the blue laser was discovered. Actually, the wavelength

405nm would correspond to the blueviolet part of the visible light, in the spectrum. This achievement is

attributed to the efforts of Shuji Nakamura of Nichia Corporation, Japan. The device utilizes a GaN diode as

its laser source. The operating current is kept between 60mA and 70mA foroptimum performance.

For writing into the disc, the power of the laser used is about 6mW. For reading from the disc, much

lesser power is required, only about 0.7mW.The GaN source can give a power of about 65mW. So, it is

an ideal choice for the laser source to be used with the Bluray disc. Due to the much lower

wavelength involved, the amorphous mark size (bit size) is small, leading to higher storage capacity on

disc of the same size, about five to six times the capacity of a DVD

A blue laser operates in the blue range of the light spectrum, ranging from about 405nm to 470nm.

Most blue laser diodes use indium gallium nitride as the material to create the laser light, although the

amount of indium included in the material varies. (Some blue laser diodes use no indium.) Some

manufacturers create blue LEDs (light-emitting diodes), which create light in a manner similar to

lasers with silicon carbide.

Blue laser beams have a smaller spot size and are more precise than red laser beams, which lets data

on blue laser optical storage discs be stored more densely. The spot size of a laser beam is one

determining factor, along with the materials in the optical disc and the way the laser is applie d to the

disc, in the size of the pits the laser makes on an optical disc. Laser beams with larger spot sizes

typically create larger pits than those with smaller pit sizes. Blue lasers are desirable because blue



UDAIPUR, RAJASTHAN


10/37

light has the shortest wavelength among visible light.

A blue laser operates at a shorter wavelength of about 405nm than a red laser at about 650nm.

A nanometer (nm) is one-billionth of a meter, one-millionth of a millimeter, and one-thousandth of a

micron. One inch is equal to about 25.4 million nanometers. A human hair is about 50,000nm wide.



UDAIPUR, RAJASTHAN


11/37

Optical Data Storage for Digital Video

Introduction

Optical data storage is commercially successful in the form of Compact Discs (CDs) for audio and

software distribution and Digital Versatile Discs (DVDs) for video distribution. CDs and DVDs lookvery similar because the fundamental optical technology for both devices is the same. This similarity

is also true for the next generation of optical data storage, which may be used for digital home theater

recording and HDTV distribution. However, CDs, DVDs and next generation products are different

in terms of specific optical components in the drive, in how data are managed and in details of the

disk structure used to store the information. These differences allow a larger volume of data to be

recorded on each successive generation. Larger data volumes translate into higher quality video and

longer playing time.



UDAIPUR, RAJASTHAN


12/37

Parameters for HD Video Storage with Optical Disks

Optical Parameters

Disk Structure Parameters

Data Management Parameters

Optical parameters include laser wavelength, objective lens numerical aperture, protective layer

thickness and free working distance. Data management parameters include data rate, video format,

HDTV play time and bitrate scheme. Disk structure parameters are user data capacity, minimum

channel bit length and tracktotrack spacing.

Optical parameter

Digital information is stored on optical disks in the form of arrangements ofdata marks in spiral tracks.

The process for exposing data marks on a recordable optical disk is shown in Fig. 1, where an input

stream of digital information is converted with an encoder and modulator into a drive signal for a

laser source. The laser source emits an intense light beam that is directed and focused onto the surface

by the objective lens. As the surface moves under the scanning spot, energy from the intense scan spot

is absorbed, and a small,localized region heats up.

fig



UDAIPUR, RAJASTHAN


13/37

The surface, under the influence of heat beyond a critical writing threshold, changes its reflective

properties. Modulation of the intense light beam is synchronous with the drive signal, so a circular

track of data marks is formed as the surface rotates. The scan spot is moved slightly as the surface

rotates to allow another track to be written on new media during the next revolution.

Data marks on prerecorded disks are fabricated by first making a master disk with the appropriate data

mark pattern. Masters for prerecorded CDs and DVDs are often exposed in a similar manner to

exposing data marks on recordable optical disks, except that the lightsensitive layer is designed to

produce pits in the master that serve as data marks in the replicas. Inexpensive replicas of the master

are made with Injectionmolding equipment.

Readout of data marks on the disk is illustrated in Fig.2, where the laser is used at a constant output

power level that does not heat the data surface beyond its thermal writing threshold. The laser beam

is directed through a beam splitter into the objective lens, where the beam is focused onto the surface.

As the data marks to be read pass under the scan spot, the reflected light is modulated. Modulatedlight is collected by illumination optics and directed by the beam splitter to servo and data optics,

which converge the light onto detectors. The detectors change light modulation into current

modulation that is amplified and decoded to

Fig 2



UDAIPUR, RAJASTHAN


14/37

produce the output data stream. A fundamental limitation to the number ofdata marks per unit area is due to

the size of the focused laser beam that illuminates the surface. Small laser spots are required to record

and read out small data marks. More data marks per unit area translate into higher capacity disks, so

evolution of optical data storage is toward smaller spot sizes.

Figure 3 shows a detailed picture of the laser irradiance approaching the surface, where irradiance is defined

as the laser power per unit area. Ideally, maximum irradiance is located at the recording material, along

with the smallest spot size s. As the distance increases away from the ideal focus, the spot size

increases and the peak irradiance decreases. A defocus distance z of only a few micrometers

dramatically reduces peak irradiance and increases spot size. An approximate formula used to

estimate the ideal spot size at best focus is s = /(sin ), where is the marginal ray angle of the

illumination optics, as shown in Fig. 1. Spot size s is the full width of the irradiance distribution at the

1/e2 (13.5%) irradiance level relative to the peak. The value of sin q is often called the numerical

aperture or NA of the optical system.

Fig 3

Instead of focusing directly on the recording surface, optical disks focus through a protective layer, as shown

in Fig.4 for a simple CDROM. The protective layer prevents dust and other contamination from directly

obstructing the laser spot at the data marks. Instead, the out offocus contamination only partially obscures



UDAIPUR, RAJASTHAN


15/37

the laser focus cone, and data can usually be recovered reliably. If the protective layer is scratched or

damaged, it can be cleaned or buffed.

As the protective layer gets thinner, the error rate increases to an unacceptable threshold due to

obscuration of the laser beam. This sensitivity decreases as NA increases, due to the smaller defocus

range associated with these systems. In addition, the free working distance separates the objective lens

from the spinning disk. This separation protects the disk against accidental contact between the

objective lens and the disk.

In order to maximize disk capacity, the optical system uses high NA and short wavelength. For

maximum contamination protection, the protective layer should be as thick as possible. However, the

combination of thick protective layer and high NA is not easily accomplished. High NA systems are

sensitive to changes in substrate thickness and disk tilt. Manufacturing variations create thickness no

uniformities, which are usually

Fig 4

a small percentage of the total disk thickness. Motor instabilities induce tilt as the disk spins. Energy from

the central portion of the spot is redistributed to concentric rings, which degrade the quality of the

read out signal. This Degrades the read out signal. Tilt causes coma, which is another form of

aberration effect, is called spherical aberration.



UDAIPUR, RAJASTHAN


16/37

Sensitivity of the spot to degradation from thickness variations and disk tilt is plotted in Fig. 5 as a

function of total protective layer thickness for two values of NA. In order to limit these effects, the

substrate is made as thin as possible without sacrificing contamination protection.

The most conservative technology is the Video CD. Its thick protective layer, relatively low NA and long

laser wavelength produce a stable system that is not very sensitive to environmental factors like dust and

scratches. The ideal spot size is about 0.78/0.5 = 1.6 micrometers. Although the cover layer is thick at 1.2

mm, the sensitivity to thickness variations and disk tilt is low because of the low NA. DVD technology

uses a shorter wavelength laser, higher NA optics and a thinner protective layer. The combination of

short wavelength and higher NA produce a spot size of about 1.1 micrometers. The protective layer

had to be made thinner, because the sensitivity to thickness variations and disk tilt is too high

otherwise.

DVDs are slightly more sensitive to dust and scratches than CDs. The net effect is not great, because higher

NA reduces the focal depth and DVDs have a more robust error management strategy.

The Advanced Optical Disk and BluRay systems both use a new blue laser source that emits 0.405

micrometer light. The Advanced Optical Disk system uses the same protective layer thickness as a



UDAIPUR, RAJASTHAN


17/37

DVD, and it uses the same NA objective lens. Due to the short wavelength, the spot size for the

Advanced Optical Disk is about 0.62 micrometers.

Sensitivity to dust and scratches is about the same as a DVD, as well as the sensitivity to thickness

variations and disk tilt. The BluRay system uses both higher NA and thinner cover layer. The spot

size is 0.405/0.85 = 0.48micrometers, which is the smallest spot size of all the technologies.

However,because of the high NA, the protective layer had to be made thin to limit sensitivity to

thickness variations and disk tilt. Therefore, BluRay disks are sensitive to dust and

scratches. The free working distance is nearly is same for all technologies

except BluRay. BluRay systems utilize more complicated lens systems due

to the high NA, so working distance had to be reduced. The integrity of this

reduced working distance is not clear at this time.

Disk Structure Parameters

The spot size created from the NA and wavelength parameters is the most important factor to determine the

tracktotrack spacing and the minimum channel bit length along the track. Several channel bits are

encoded into each data mark. The number of channel bits per data mark depends on the modulation

scheme. The relatively large spot produces relatively large data marks and correspondingly wide

tracks and large channelbit lengths. Progressively smaller spot sizes enable smaller track spacing and

shorter channel bit lengths.



UDAIPUR, RAJASTHAN


18/37

Fig 6

To the user, all generations of optical disks look very similar. They all are round disks that are

approximately 120 mm in diameter, have a central mounting hole and are approximately 1.2 mm

thick. Through many years of experience with CDs, this format has proven effective and mechanically

reliable. However, the manner in which data layers are arranged on the disk depends on the

technology used. For example, the CD uses a simple 1.2 mm thick substrate, as shown in Fig. 6A. Data

are recorded on only one side of the disk, through the clear 1.2 mm substrate, which also serves as the

protective layer. DVDs, Warner HDDVDs and Advanced Optical Disks use the format shown in Fig.

6B, where two 0.6 mm substrates are bonded together and the data are recorded on the bond side of

each substrate. DVDs also allow more two layers per side (A, B in Fig. 6B), where the layers are

separated by a thin adhesive spacer. The two layers are fabricated before bonding at the same time as

the individual 0.6 mm substrates. Like the CD, data are recorded and read through the clear

substrates. It is likely that the Warner HDDVD and Advanced Optical Disk will also take advantage

of this multiplelayer concept. A potential implementation of the BluRay disk is shown in Fig. 6C,

where the protective layers on each side are very thin at 0.1 mm. In this case, data are recorded on the

substrate, which does not serve as the protective layer. Instead, a protective layer resin is spun on and



UDAIPUR, RAJASTHAN


19/37

hardened or a thin protective sheet is bonded on each side of the substrate. Because of the thin

protective layer, the BluRay disk must also be used with a cartridge.

The only optical disk technology that plans to use a Cartridge is the BluRay system. The BluRay

cartridge is necessary for contamination Protection, but the working distance of around 0.1 mm and

protective layer thickness of 0.1 mm are large compared to the contact recording.

The technology for making disks is very similar to existing DVD technology. Higherresolution

mastering machines and finer control over the injection molding process should produce the required

changes without substantially retooling the industry. The BluRay system requires the most changes

of the three, including a blue laser, detector, and advanced objective lens. BluRay also requires new

disk and cartridge manufacturing technology, which may be difficult to implement in a short time

frame.

Data Management Parameters

The logical organization of data on the disk and how those data are used are considerations for data

management. Data management considerations have important implications in the application of optical disk

technology to storage for HDTV. For example, simply using a more advanced error correction scheme on

DVDs allows a 30% higher disk capacity compared to CDs. Data rate, video format, bit rate scheme and

HDTV play time are all data management issues.

There is a basic difference in data management between CDs and DVDs. Since CDs were designed for

audio, data are managed in a manner similar to data management for magnetic tape. Long, contiguous files

are used that are not easily subdivided and written in a random access pattern. Efficient data retrieval is

accomplished when these long files are read out in a contiguous fashion. To be sure, CDs are much more

efficient that magnetic tape for pseudorandom access, but the management philosophy is the same. On the

other hand, DVDs are more like magnetic hard disks, where the file structure is designed to be used in

randomaccess architecture. That is, efficient recovery of variable length files is achieved. In addition, the

Original error correction strategy for CDs was designed for error concealment when listening to audio,

where DVDs utilize true error correction. Later generations of optical disks also follow the DVD model.

The randomaccess nature of DVDs allows very efficient methods for data compression. For example,MPEG2 with variable bit rate allows data to be read out from the disk as they are required, rather than

supplying data at a constant rate. Slowly moving scenes, like love scenes or conversations, require much less

information per frame than a fastmoving car chase or explosion. In these fastmoving scenes, the maximum

amount of information per scene is limited only by the maximum data rate of the player. For HDTV,

acceptable picture quality is obtained by using MPEG2 with a maximum data rate of about 1325 Mbps for

most scenes. During a slow scene, not as many files are accessed, and much less storage area on the disk is

used. This architecture leaves room on the disk for the data associated with fastermoving scenes.D e p a r t m e n t o f E l e c t r o n i c s & C o m m u n i c a t i o n E n g i n e e r i n g


UDAIPUR, RAJASTHAN


20/37

Fixedrate schemes, like magnetic tape, supply data at a constant rate, no matter what the requirements of

the scene. During fastmoving scenes, the data stream from the tape supplies an adequate data rate. The tape

speed and data rate for these devices are set by the upper limit of the scene requirements. Since the tape does

not slow down during slower scenes, the data stream is padded at these times with useless information that

takes up valuable storage area on the tape. Overall, the random access architecture of optical disks is a much

more efficient way to use the available storage area. That is, optical disks do not require as many gigabytes

of userdata capacity for an equivalent length and quality HDTV presentation.

It is not practical to store HDTV on CDs and DVDs with MPEG 2. For CDs, special multiplebeam

readout or high velocity disk dives could produce the data rate, which is an advantage of the fixed

bitrate scheme. However, the play time would be only a few minutes, at best. DVDs are not capable

of the 13 Mbps random data rate to support MPEG2. The Advanced Optical Disk exhibits acceptable

data rate and reasonable user data capacity for up to two hours of HDTV per side compressed with

variable bitrate MPEG2. Bluray has slightly higher capacity and data rate. The twohour play timefor HDTV with BluRay in Table I is really a specification for realtime recording, which is not easily

compressed into an efficient variablerate scheme. BluRay should easily provide two hours or longer

of prerecorded HDTV per side compressed with MPEG2. MPEG2 is a technique for compressing

video data and replaying the data associated with certain rules that are defined in the MPEG 2

specifications. The action of the optical disk system is not to compress data or interpret the video

information rules. Instead, the optical disk system only stores and retrieves data on command from

the video operating system. Therefore, as video operating systems and associated compressiontechnology become more advanced, no fundamental changes are required to the optical disk system.

MPEG4 technology is an advanced video compression scheme that utilizes advanced prefiltering

and postfiltering, in addition to a rulebased algorithm. Estimated improvement in compression is a

around a factor of three beyond MPEG2.

Different Formats of Blueray Disc

BDROM : A read only format developed for prerecorded

content.

BDR : A write once format developed for PC storage.



UDAIPUR, RAJASTHAN


21/37

BDRW : A rewritable format developed for PC storage.

BDRE : A rewritable format developed for HDTV

recording.

Two Versions of Recording

One Time Recording

Making permanent changes to a disc. If we use BDR the material on the disc itself is changed forever.

There is no way to get the material back into its old state. The recording material is crystalline in

nature. As scan spot falls on the surface it changes to amorphous. We cannot change it back to crystal

state.

Record Many Times

If we use a BDRW the material on the disc itself changes, but can be changed back again .We can do

this as long as the material doesnt get worn out. By heating up the crystals, they change form. Now

when we quickly cool them, they stay in that form itself. That is the material is changed from crystal

state to amorphous state.



UDAIPUR, RAJASTHAN


22/37

Now, if we want to erase the BDRW, we have to make sure that we lose all the data. So we want to

get rid of that amorphous state. By heating up the material again, but this time taking more time and

less heat, the material gradually wants to take its old form again, and thus the information is erased.

This state is called the crystalline state.

So, by very quickly heating it and very quickly cooling it, give the crystal another state (Amorphous state)

which thus contains the data and by very quite slowly heating it and cooling it, we can give the crystals their

old form back (crystalline state) which contains no more data. Its a constant change of phases. And so it is

called as phase change recording.

Bluray Disc Structure



UDAIPUR, RAJASTHAN


23/37

The structure of the BD is as shown. The 0.1mm transparent cover layer is made of a spincoated UV resin.

It is formed by sandwiching a transparent layer between a protective coating and a bonding layer. This layer

offers excellent birefringence. Beneath, there is a layer of Antis layer acts as a heat sink, dissipating the

excess heat during the write process. A spacer layer made of ZnSSiO2 comes next. Then, the recording

layer made of Ag, In, Sb, Te, Ge comes. Grooves are formed on this layer for recording reflective layer of

Ag alloy falls beneath and finally a plastic substrate comes.

The key features of the technology are introduced as follows:

Highly flat and smooth cover layer:

At the high speed recording rate involved, the linear velocity of the disc reaches 20m/s or more and as a

result accurate focus control becomes difficult. Various experiments showed that flatness and

smoothness of the transparent cover layer have a marked influence on the focus control capability.

This end is achieved by using the spin coating method for obtaining the transparent cover layer. Thus

stable record ability at high speed recording is secured.



UDAIPUR, RAJASTHAN


24/37

Phase change film for high speed recording:

The phase change film should have high re-crystallization speed to enable direct recording at

the high linear velocities involved. A recording layer made of Ag, In, Sb, Te, Ge meets thispurpose.

Super advanced rapid cooling structure:

The excess heat from the LASER irradiation causes distortion of the recorded mark edge. So,to diffuse the remaining excess heat, a transparent dielectric film of high thermalconductivity, for example, AlN is used.



UDAIPUR, RAJASTHAN


25/37



UDAIPUR, RAJASTHAN


26/37

Basic Bluray Disc Characteristics

Large Recording Capacity

The Bluray disc enables the recording, rewriting and playback of HD video unto 27 GB

of data on a single sided single layer. It is enough to put 2.5 hours of HDTV recording

on it. It also can record over 13 hours of standard TV broadcasting using the VHS/

standard definition picture quality.

High Speed

It has a data transfer rate of 36 Mbps. Because of this high speed transfer rates it can alsorecord the data in very little time. In a perfect environment it would take about 2.5 hours tofill the entire BD with 27 GB of data. More than enough transfer capacity for real timerecording and playback.

Resistant to Scratches and Fingerprints

The protective layer is hard enough to prevent accidental abrasions and allowsfingerprints to be removed by wiping the disc with a tissue.



UDAIPUR, RAJASTHAN


27/37

Characteristics of Ideal Communication

1. Speed:The blue laser technology will allow DVD recording devices to record data at aspeed of 36Mbps. Developing companies such a TDK also stated that they will be able toincrease the recording speed up to 72Mbps and 144Mbps. Developing companies such asToshiba and NEC have been working on this technology and have already developed the

blue laser standard.

2. Reliability:Storage mediums used by blue laser burners will provide high reliablebackup at affordable prices. Media types will provide a 50 year data life. They will alsoemploy a new dual shutter cartridge to minimize contamination and protect valuable datastored on a disc.

3. Quality: Media storage devices using this technology will have a quality similar to thequality of red laser storage devices. Optical discs have to be used in a safe way. They should

be in the case they come in or in the device using it. This is to avoid scratching of the discswhich can cause data on a disc to be unreadable. Laser printers would me more precise thanregular laser printers that use red laser, because of the shorter wavelength that blue laser has.

4. Ease of Use: DVD recording devices are very simple to use. Even children can usethem. There are no complexities to the use of blue laser recording devices. They are used

just like any regular red laser DVD recording device. An easy to use optical disc cartridge

protects the optical disc's recording and playback phase from dust and fingerprints.

5. Cost:The price ofan optical disc recording device using blue ray will start off with ahigh price tag around $1700. Just like any computer related devices that are new the pricewill decrease as time passes. It has a high storage capacity which is up to 60 GB on a dualsided DVD.

6. Safety and Security: Blue laser light helps in detecting some chemical andbiological weapons because it causes them to give off light. So it could be used in

airports and other places that have security screening to detect such a weapon.

How does Blu-ray disc work?

History of Technology



UDAIPUR, RAJASTHAN


28/37

The challenge to write more information on disk Shiju Nakamura is credited withinventing the blue diode laser and blue, green, and white LEDs. Nakamura was

working at Nichia Chemical Industries in Japan when he developed the blue laser in

1995.

Description of how this technology works

Blue lasers have a wavelength of 405 nanometers, shorter than that of red lasers, which havea wavelength of around 650 nanometers and are used for reading and writing DVD and CDdiscs. The shorter wavelength means that the laser can register smaller dots on a disc andmore data can be stored. As a result, blue laser technology has been adopted for thedevelopment of next-generation optical discs.

1. Using double infrared frequency to create the wavelength for blue light.

2. A blue laser operates in the blue range of the light spectrum, ranging from about 405nm to

470nm.

3. Most blue laser diodes use indium, gallium nitride as the material to create the laser light.

4. Blue laser beams have a smaller spot size and are more precise than red laser beams,which lets data on blue laser optical storage discs be stored more densely.

5. The spot size of a laser beam is one determining factor, along with the materials in theoptical disc and the way the laser is applied to the disc, in the size of the pits the laser makeson an optical disc.

6. Laser beams with larger spot sizes typically create larger pits than those with smaller pitsizes.

Comparisons

While current optical disc technologies such as CD, DVD, DVD-R, DVD+R, DVD-RW andDVD+RW use a red laser to read and write data, the new format uses a blue laser instead,hence the name Blu-ray. The benefit of using a blue laser is that it has a shorter wavelength(405 nanometer) than a red laser (650 nanometer), which means that it's possible to focus thelaser beam with even greater precision. This allows data to be packed more tightly on thedisc and makes it possible to fit more data on the same size disc. Despite the different typeof lasers used, Blu-ray Disc Recorders will be made compatible with current red-lasertechnologies and allow playback of CDs and DVDs.The following diagram shows the



UDAIPUR, RAJASTHAN


29/37

comparison between different storage Techn.

Blu-ray Disc and HD-DVD

The HDDVD format, originally called AOD or Advanced Optical Disc, is based on much oftodays DVD principles and as a result, suffers from many of its limitations. The format doesnot provide as big of a technological step as Bluray Disc. For example, its prerecordedcapacities are only 15 GB for a single layer disc, or 30 GB for a double layer disc. Bluray

Disc provides 67% more capacity per layer at 25 GB for a single layer and 50GB for adouble layer disc.

Although the HDDVD format claims it keeps initial investments for disc replicates andmedia manufacturers as low as possible, they still need to make substantial investments inmodifying their production equipment to create HDDVDs. But whats more important isthat HDDVD can be seen as just a transition technology, with a capacity not sufficient for

the long term. It might not offer enough space to hold a High Definition feature along withbonus material in HD quality and additional material that can be revealed upon authorizationvia a network. When two discs are needed, this will degrade the socalled cost benefitsubstantially. It is even possible that the HDDVD specification will be followed up by a



UDAIPUR, RAJASTHAN


30/37

renewed version of the technology within a few years, requiring media manufacturers toupgrade their existing production lines again, and consumers to replace their existing

playback/recording equipment. On the other hand, the Bluray Disc format was designed tobe a viable technology for a period of at least 10 to 15 years.

Also on the application layer, the HDDVD format incorporates many compromises. As

the capacity is not likely to be sufficient to encode a fulllength feature plus additionalbonus materials using the MPEG2 format, different and stronger encoding formatsneed to be used. Although Bluray Disc offers these advanced codec as well, the disc hassuch high capacity that publishers can still use the MPEG2 encoding format at bitrates up to 54 Mbit/sec. As MPEG2 is the defacto standard used in almost anyindustry involved in digital video (DVD, HDTV, digital broadcast), many authoring

solutions are available. Chances are high that a full line MPEG 2 encoding suite isalready available, which can be used with no or minor adaptations to encode High

Definition content for Bluray Disc. But perhaps the most important factor for thesuccess of Bluray Disc is its overwhelming industrywide support. Almost allconsumer electronics companies in the world (combined market share of about 90%)

and the worlds two largest computer companies support the Bluray Disc format

13. Advantages

The main advantages of the Bluray disc are

More storage capacity on a disc of the same size

The data storage capacity on a Bluray disc is 27GB on a single layer and 54GB on duallayer, which is about five to six times the capacity of a DVD. It would mean about 2.5

hours of HDTV video and about 13 hours of SDTV video.

High data transfer rate.

The basic data transfer rate in Bluray disc is about 36Mbps which is about three timesthat of a DVD and thirty times that of a CD.

Available in different versions like ROM, R and RE



UDAIPUR, RAJASTHAN


31/37

The BD is available in different versions like the ROM (write once), R (read only), RE(rewritable).

Backward compatible

The BD drives are designed to be backward compatible, i.e. CDs and DVDs work equallywell with the BD drives.

Strong content protection

The features of the content protection system are

Format Developed with Input from Motion Picture Studios.

Strong Copy Protection.

Renewability with Renewal Key Block and Device Key.

Enhanced Encryption Algorithm: AES 128 bit.

Physical Hookagainst Bit by Bit Encrypted Content Copy.

Titlebased Expandable Content Control File.

Production Process Control Works against Professional Piracy.

Public Key Based Authentication in PC Environment.

Compatible with analog and digital transmission

The BD fares well with analog as well as digital transmission. It offers the only means to therecording and reproducing of digital HDTV video. Format for encoding analog signals also,called SESF (Self Encoded Stream Format) is also incorporated into the BD.

Higher disc life



UDAIPUR, RAJASTHAN


32/37

In the case of ordinary discs, the disc life is less fir the rewritable versions, as rewriting isdone repeatedly to one area of the disc most probably, the inner perimeter. This limits

the disc life. But, the BDFS(Bluray Disc File Structure is designed so as to avoid thisproblem, by using a system that uses free disc spaces with equal frequency.

15. Applications

High Definition Television Recording

High Definition Video Distribution

High Definition Camcorder Archiving

Mass Data Storage

Digital Asset Management and Professional Storage

The Bluray Disc format was designed to offer the best performance and features for a wide

variety of applications. High Definition video distribution is one of the key features of Blu

ray Disc, but the formats versatile design and topoftheline specifications mean that it issuitable for a full range of other purposes as well.

15.4 Mass Data Storage

In its day, CDR/RW meant a huge increase in storage capacity compared to traditionalstorage media with its 650 MB. Then DVD surpassed this amount by offering 4.7 to 8.5

GB of storage, an impressive 5 to 10 times increase. Now consumers demand an even

bigger storage capacity. The growing number of broadband connections allowing

consumers to download vast amounts of data, as well as the ever increasing audio,

video and photo capabilities of personal computers has lead to yet another level in data

storage requirements. In addition, commercial storage requirements are growing

exponentially due to the proliferation of email and the migration to paperless

processes. The Bluray Disc format again offers 5 to 10 times as much capacity asD e p a r t m e n t o f E l e c t r o n i c s & C o m m u n i c a t i o n E n g i n e e r i n g


UDAIPUR, RAJASTHAN


33/37

traditional DVD resulting in 25 to 50 GB of data to be stored on a single rewritable or

recordable disc. As Bluray Disc uses the same form factor as CD and DVD, this allowsfor Bluray Disc drives that can still read and write to CD and DVD media as well.

16.Requirements

1) Blue laser

2) Detector

3) Advanced objective lens

4) New disk and cartridge manufacturing technologies

17.Challenges

High cost

The technology is not that popular and hence, the price of the BD recorders and playersavailable in the market is very high.

HD-DVD

The HDDVD (High Definition DVD) based on the Advanced Optical System championed

by Toshiba and NEC is the primary rival to BD in the market. Though its data storagedensity is lower, it has lower manufacturing costs also, which may prove challenging to theBluray disc.

Future Developments

Efforts are progressing on many fronts to make the Bluray discs, players and recorders

cheaper. On 15 April 2004 for instance, Sony and Toppan Printing announced the successfulD e p a r t m e n t o f E l e c t r o n i c s & C o m m u n i c a t i o n E n g i n e e r i n g


UDAIPUR, RAJASTHAN


34/37

development of a Bluray Disc that is 51% (by mass) composed of paper, which could reduceproduction costs and improve its environmental friendliness. The cost would comedown as BD becomes more and more popular.

TDK has been researching the hard coat technology that will provide protection

against fingerprints and scratches. Colloidal silica dispersed UVcurable resin is being

used for the researches and results are encouraging.

Figure shows the cross section of the disc being developed.

Conclusion

In conclusion the Blue-ray Disc is a technology platform that can store sound and videowhile maintaining high quality and also access the stored content in an easy-to-use way.Blue lasers have a shorter wavelength, which means the laser beam can be focused onto

a smaller area of the disc surface. In turn, this means less real estate is needed to store

one bit of data, and so more data can be stored on a disc. This will be important in the

coming broadband era as content distribution becomes increasingly diversified.

Companies involved in the development will respectively make products that take full

advantage of Blue-ray Disc's large capacity and high-speed data transfer rate. They



UDAIPUR, RAJASTHAN


35/37

are also aiming to further enhance the appeal of the new format through developing a

larger capacity, such as over 30GB on a single sided single layer disc and over 50GB on

a single sided double layer disc. Adoption of the Blue-ray Disc in a variety of

applications including PC data storage and high definition video software is also being

considered. There is a lot of talk about blue-laser-based systems being focused around

high-definition television, which has heavy data needs. But Blue-ray Disc groups are

also considering development of write-once and read-only formats for use with PCs.

Prototype blue-laser-based optical disc systems have been around for more than a

year. However, one problem has hampered development of commercial systems: cost.

A sample blue-laser diode currently costs around $1000, making consumer products

based on the parts unrealistic. However, Nichia, the major source for blue lasers, is

expected to begin commercial production this year and the price of a blue-laser diode is

expected to tumble once the company begins turning them out in volume. The DVD

forum may or may not invite the blue-ray light into is era but the 27GB disc is not far

off in practically disturbing the DVD wave.

REFERENCES

Research Papers:



UDAIPUR, RAJASTHAN


36/37

1) Wobble-address format of the blu-ray disc. By S. Furumiya, S. Kobayashi, B.Stek, H. Ishibashi, T. Yamagami, K. Schep: Presented at ISOM/ODS Hawaii, July 2002 .

2) Millipede- Nanotechnology Entering Data Storage, By P. P. Vettiger, G. Cross,M. Despont, U. Drechsler, U. Drig, B. Gotsmann, W. Hberle, M. A. Lantz, H. E.Rothuizen, R. Stutz, and G. K. Binnig:

3) 34 GB Multilevel-enabled Rewritable System using Blue Laser and High NAOptics. By H. Hieslmair, J. Stinebaugh, T. Wong, M. ONeill, M. Kuijper, G. Langereis:Published at ISOM/ODS Hawai, July 2002.

Websites:

http://www.licensing.philips.com/

http://www.almaden.ibm.com/st/disciplines/storage/



UDAIPUR, RAJASTHAN
http://www.licensing.philips.com/http://www.almaden.ibm.com/st/disciplines/storage/http://www.almaden.ibm.com/st/disciplines/storage/http://www.licensing.philips.com/


37/37

Blu‐ray Disc-2

Documents