“DEPARTMENT OF ELECTRONICS & COMMUNICATION”

SEMINAR REPORT

ON

“BLU-RAY DISC”

SUBMITTED TO :- SUBMITTED BY :-

Mr. Rohit Tripathi Sonal Singh

(Seminar Incharge) EC 4th year

(0616431111)

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ACKNOWLEDMENT

I would like to thank everyone who helped to see this seminar to completion. In particular, I would like to thank my seminar incharge Mr. Rohit Tripathi for his moral support and guidance to complete my seminar on time.

I express my gratitude to all my friends and classmates for their support and help in this seminar.

Last but not the least I wish to express my gratitude to God almighty for his abundant blessings without which this seminar would not have been successful.

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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 usin g a laser with a nice colour.

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INDEX

INTRODUCTION………………………………………………..1-5

1. HISTORY OF BLU-RAY DISC………………………………..61.1 FIRST GENERATION………………………………….61.2 SECOND GENERATION…………………………….61.3 THIRD GENERATION…………………………………6-7

2. GLOSSARY OF TERMS2.1 HDTV……………………………………………………….82.2 MPEG………………………………………………………8-9

2.3 GIGABYTE………………………………………….92.4 LAYER………………………………………………………9-102.5 SDTV……………………………………………………….102.6 NUMERICAL APERTURE……………………………10-112.7 BLUE LASER………………………………………………11-12

3. OPTICAL DATA STORAGE FOR DIGITAL VIDEO3.1 INTRODUCTION…………………………………………163.2 PARAMETERS FOR HD VIDEO STORAGE WITH OPTICAL

DISCS……………………………………………………….163.2.1 OPTICAL PARA METER…………………………16-223.2.2 DISK STRUCTURE PARAMETERS……………22-243.2.3 DATA MANAGEMENT PARAMETERS…….24-26

4. DIFFERENT FORMATS OF BD………………………………275. TWO VERSIONS OF RECORDING…………………………28

5.1 ONE TIME RECORDING……………………………..285.2 RECORD MANY TIMES……………………………….28-29

6. BLU-RAY DISC STRUCTURE………………………………….30-317. BLU-RAY DISC CHARACTERISTICS………………………..33

7.1 LARGE RECORDING CAPACITY……………………337.2 HIGH SPEED………………………………………………337.3 RESISTANCE TO SCRATCHES 7.4 AND FINGERPRINTS…………………………………..33

8. BLU-RAY FOUNDERS………………………………………………….349. CHARACTERISTICS OF IDEAL COMMUNICATION………..3510.HOW DOES BLU-RAY DISC WORK? ……………………………36-37

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11.COMPARISONS………………………………………………………….3812.BLU-RAY DISC AND HD-DVD………………………………………39-4013.ADVANTAGES OF BD………………………………………………….41-4214.THE BLU-RAY IMPACT………………………………………..........4315.APPLICATIONS……………………………………………………………44

15.1 HIGH DEFINITION TELEPHONE RECORDING………4415.2 HIGH DEFINITION VIDEO DISTRIBUTION……………4515.3 HIGH DEFINITION CAMCORDER ARCHIVING………4515.4 MASS DATA STORAGE……………………………………….4615.5 DIGITAL ASSET MANAGEMENT AND

PROFESSIONAL STORAGE……………………………………………………………46

16.REQUIREMENTS……………………………………………………………4717.CHALLENGES………………………………………………………………….4718.FUTURE DEVELOPMENTS……………………………………………….4819.CONCLUSION………………………………………………………………….4920.REFERENCES……………………………………………………………………50

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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.

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The Blu-ray Disc is a technology platform that can store sound and video while

maintaining high quality and 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.

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

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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.

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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 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.

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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

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1. History of Blu‐ray Disc

1.1 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 pre recorded, recordable and rewritable media, offering the best ‐quality and features consumers could wish for themselves, at very low costs.

1.2 Second Generation

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

1.3 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 Blu ray Disc, the only format ‐

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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 ofBlu ray 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. Blu ray 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 CD ROM introduced – not popular at first. More powerful PCs lead‐ ‐ to demand for multimedia, image processing and larger applications. Growth in sales brings prices down.• 1990’s CD R and CD RW introduced – big success.‐ ‐ ‐• 1996 DVD introduced‐• 1999 DVD becomes mainstream‐• 2003 BD introduced‐

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2. Glossary of Terms

2.1 HDTV (High Definition Video)

This high resolution 16:9 ratio, progressive scan format can now be recorded to standard mini DV cassettes. Consumer high definition cameras are becoming available but this is currently an expensive, niche market. It is also possible to capture video using inexpensive webcams. These normally connect to a computer via USB. While they are much cheaper than DV cameras, webcams offer lower quality and less flexibility for editing purposes, as they do not capture video in DV format. Digital video is available on many portable devices from digital stills cameras to mobile phones. This is contributing to the emergence of digital video as a standard technology used and shared by people on a daily basis.

2.2 MPEG

MPEG, the Moving Picture Experts Group, overseen by the International Standards Organization (ISO), develops standards for digital video and digital audio compression. MPEG 1 with a default resolution of 352x240 was designed‐ specifically for Video CD and CD media and is often used in CD ROMs.‐ ‐ ‐

MPEG 1 audio layer 3 (MP3) compression evolved from early MPEG work. ‐ ‐MPEG1 is an established, medium quality format (similar to VHS) supported by all players and platforms. Although not the best quality, it will work well on older specification machines.

MPEG 2 compression (as used for DVD movies and digital television set top ‐ ‐boxes) is an excellent format for distributing video, as it offers high quality and smaller file sizes than DV. Due to the way it compresses video MPEG 2‐ ‐encoded footage is more problematic to edit than DV footage. Despite this, MPEG2 is becoming more common as a capture format. MPEG 2 uses variable bit rates allowing frames to be encoded with more or less data depending on

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their contents. Most editing software now supports MPEG2 editing. Editing and encoding MPEG2 requires more processing power than DVD and should be done on well specified machines. It is not suitable for internet delivery.

MPEG 4 is a set of video and audio standards intended to deliver quality video ‐over limited bandwidths that also support a range of other media types such as text, still image and animation. MPEG 4 offers high quality, scalable streaming ‐over a range of bandwidths, including those provided by mobile networks. The standards also include components and elements that allow the viewer to interact with the picture on the screen or to manipulate individual elements in real time. The MPEG4 format is a container for various versions called layers. There are different implementations, some of which are proprietary and not compliant with the ISO MPEG4 standard. It was initially thought that MPEG4 would become the default format for video over the internet. With support from Apple, Real Networks and others this may still be the case. However, problems over licensing costs and the lack of digital rights management in the standard made many content providers slow to embrace it. These issues are being tackled but it also faces competition from proprietary formats such as Windows Media. MPEG4 is beginning to be supported in other areas such as mobile video (3G), mobile television, set top boxes and video on demand ‐(VOD).

2.3 Gigabyte (GB)

A gigabyte equals about 1,000 megabytes (MB). A Blu ray Disc capable of ‐recording 50 GB therefore stores about 50,000 Megabytes

2.4 Layer

In Blu ray 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 Blu ray Disc device will first read from or record to one layer, and ‐then re focuses on the second layer. All this is done automatically without any ‐user interference. A double layer Blu ray Disc can store upto 50 GB of data.‐

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2.5 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.

2.6 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.

Image forming 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

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length of the objective. The angle μ is one half the angular aperture (A) and is ‐related to the numerical aperture through the following equation:

Numerical Aperture (NA) = n (sin μ)

Where n is the refractive index of the imaging medium between the front lensof 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 μ for μ 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 μ whose maximum value is 90°. The sin of the angle μ, 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).

2.7 THE BLUE LASER

The laser used with the Blu ray 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 blue violet 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 for optimum 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 Blu ray 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

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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 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.

Blue Laser Development

Shiju Nakamura is credited with inventing 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. It’s a technology many large

corporations had been trying to develop for several years.

Nakamura had worked with LEDs and lasers for several years before tackling

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blue lasers in the late 1980s. Because most research at the time focused on

using zinc selenide as the laser material, Nakamura decided to work with

gallium nitride. He spent two years perfecting a technique for growing high-

quality gallium nitride crystals, something other researchers had been unable

to achieve.

Finally, Nakamura had the materials necessary to create blue LEDs, which he

did in 1993. He followed with green LEDs and a blue laser diode in the next

few years. He says the biggest commercial use for blue lasers should be DVD

players.

Putting Blue Lasers to Work

Blue lasers could appear in a variety of business applications, including high-

density DVDs, laser printers, and lighting situations.

HD DVDs: HD (high-definition) DVDs using blue laser light could lead to five

or six times the storage capacity possible using red laser light on a DVD. Blue

laser light could create HD CDs, too.

Because blue lasers can increase the capacity of optical discs by five-fold or

more, they give manufacturers a few options for their digital files.

Manufacturers could choose to burn additional data onto the disc while

keeping the same digital quality, potentially making CDs containing 50 to 75

songs. Manufacturers also could choose to use blue laser to increase the

quality level of the video or audio recording. Keep in mind that nearly all DVDs

using the MPEG-2 standard automatically contain some compression of the

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video file, which allows the file to fit on the disc. With an HD DVD,

manufacturers could choose to use no compression on the video file, which

should improve file quality.

Light bulbs: With green and red lasers already available, development of a

blue laser would be the final piece of the laser puzzle among primary colors.

By using all three colors of lasers, a researcher could create a device that

would mix the laser light and create white light, which, at some point, could

replace the common light bulb. If you combine red, green, and blue laser light,

you can produce light with greater brilliance and greater efficiency than

currently is available with fluorescent lights.

Creating LEDs in this manner can be of particular help in areas where light

bulbs are expensive and difficult to replace. An LED can burn for several times

as long as a light bulb for about one-fourth the operating cost because most of

the LED’s energy is involved in creating light, rather than creating heat energy.

Traditional light bulbs create a lot of heat along with the light.

LEDs already are used in many traffic lights, where traditional bulbs usually last

less than one year, can be tough to see in sunlight, and fail suddenly. LEDs in a

traffic light should last at least five years, remain highly visible in sunlight, and

gradually fade in intensity rather than failing suddenly.

Medicine: Scientists already are experimenting with blue lasers in

discovering certain types of cancer. Using an endoscope, researchers have had

some success finding tumors using a blue laser light inside the patient’s

stomach and intestinal tract.

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Printing: Laser printers using blue laser light would be smaller and more

precise than today’s laser printers, which use red laser light. Because of blue

laser light’s smaller wavelength, the laser mechanism inside a printer that uses

blue laser light could be smaller, leading to smaller printers. Print resolution

using blue lasers would be at least double that of today’s top laser printers,

too; some researchers estimate resolution as sharp as 2,400dpi in a blue laser

printer. Blue laser could play a role in full-color scanners and fax machines,

too.

Security: After the terrorist attacks of Sept. 11, fears have increased over

additional attacks using biological or chemical weapons. However, blue laser

light causes some chemical and biological agents to give off light, even though

those agents are invisible to the naked eye, which might let security screening

personnel spot a biological agent during a routine search or as the agent

comes through customs.

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3. Optical Data Storage for Digital Video

3.1 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 look very 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.

3.2 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 bit rate scheme. Disk structure parameters are user data capacity, minimum ‐channel bit length and track to track spacing.‐ ‐

3.2.1Optical parameter

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

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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. 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, soa circular track of data marks is formed as the surface rotates. The scan spot ismoved slightly as the surface rotates to allow another track to be written onnew 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 light sensitive 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 Injection molding equipment.‐

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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. Modulated light 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

produce the output data stream. A fundamental limitation to the number of

data marks per unit area is due to the size of the focused laser beam thatilluminates the surface. Small laser spots are required to record and read outsmall data marks. More data marks per unit area translate into highercapacity disks, so evolution of optical data storage is toward smaller spotsizes.

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

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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 δz 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 = λ/(sin θ), where θ 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 CD ROM. 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 the laser focus cone, and data canusually 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

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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 asthe disk spins. Energy from the central portion of the spot is redistributed toconcentric rings, which degrade the quality of the read out signal. This Degrades the read out signal. Tilt causes coma, which is another form ofaberration effect, is called spherical aberration.

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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 ashorter wavelength laser, higher NA optics and a thinner protective layer. Thecombination of short wavelength and higher NA produce a spot size of about1.1 micrometers. The protective layer had to be made thinner, because thesensitivity to thickness variations and disk tilt is too high otherwise. DVDs

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are slightly more sensitive to dust and scratches than CDs. The net effect isnot great, because higher NA reduces the focal depth and DVDs have a morerobust error management strategy.

The Advanced Optical Disk and Blu Ray 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 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 thesensitivity to thickness variations and disk tilt. The Blu Ray 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 limitsensitivity to thickness variations and disk tilt. Therefore, Blu Ray disks are‐sensitive to dust and scratches. The free working distance is nearly is same forall technologies except Blu Ray. Blu Ray systems utilize more complicated‐ ‐lens systems due to the high NA, so working distance had to be reduced. Theintegrity of this reduced working distance is not clear at this time.

3.2.2 Disk Structure Parameters

The spot size created from the NA and wavelength parameters is the most important factor to determine the track to track 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 channel bit lengths. ‐Progressively smaller spot sizes enable smaller track spacing and shorter channel bit lengths.

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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 HD DVDs 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 Diskwill also take advantage of this multiple layer concept. A potential ‐implementation of the Blu Ray 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

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the substrate, which does not serve as the protective layer. Instead, a protective layer resin is spun on and hardened or a thin protective sheet isbonded on each side of the substrate. Because of the thin protective layer, theBlu Ray disk must also be used with a cartridge.‐

The only optical disk technology that plans to use a Cartridge is the Blu Ray ‐system. The Blu Ray 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. Higher resolution mastering machines and finer control over the injection ‐molding process should produce the required changes without substantially retooling the industry. The Blu Ray system requires the most changes of the ‐three, including a blue laser, detector, and advanced objective lens. Blu Ray ‐also requires new disk and cartridge manufacturing technology, which may be difficult to implement in a short time frame.

3.2.3 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

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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 random access 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 random access nature of DVDs allows very efficient methods for data ‐compression. For example, MPEG 2 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 fast moving car chase or explosion. In ‐these fast moving 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 MPEG 2 with a maximum data rate of ‐about 13 25 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 faster moving scenes.‐

Fixed rate schemes, like magnetic tape, supply data at a constant rate, no ‐matter what the requirements of the scene. During fast moving 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 user data 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 multiple beam readout or high velocity disk dives could produce the ‐data rate, which is an advantage of the fixed bit rate 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 MPEG 2. 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 MPEG 2. Blu ray has ‐ ‐

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slightly higher capacity and data rate. The two hour play time for HDTV with ‐Blu Ray in Table I is really a specification for realtime recording, which is not ‐easily compressed into an efficient variable rate scheme. Blu Ray should easily ‐ ‐provide two hours or longer of prerecorded HDTV per side compressed with MPEG 2.‐

MPEG 2 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 compression technology become more advanced, no fundamental changes are required to the optical disk system. MPEG 4 technology is an advanced video compression scheme that utilizes ‐advanced pre filtering and post filtering, in addition to a rule based algorithm. ‐ ‐ ‐Estimated improvement in compression is a around a factor of three beyond MPEG 2.‐

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4. Different Formats of Blue‐ray Disc

BD‐ROM : A read only format developed for prerecorded content.

BD‐R : A write once format developed for PC storage.

BD‐RW : A rewritable format developed for PC storage.

BD‐RE : A rewritable format developed for HDTV recording.

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5. Two Versions of Recording

5.1 One Time Recording

Making permanent changes to a disc. If we use BD R 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.

5.2 Record Many Times

If we use a BD RW the material on the disc itself changes, but can be changed ‐back again .We can do this as long as the material doesn’t 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.

Now, if we want to erase the BD RW, 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. It’s a constant change of phases. And so it is called as phase change recording.

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Data is stored in the form of grooves, on an optical disc. Next to the grooves, there are lands. Lands are the borders between the grooves. Grooves and lands have a sinus form. This is called a wobbled groove. In the groove, pits are formed to store data.

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6. Blu‐ray Disc Structure

The structure of the BD is as shown. The 0.1mm transparent cover layer is made of a spin coated 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 ZnS SiO2 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.

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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.

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 this purpose.

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 di electric ‐film of high thermal conductivity, for example, AlN is used.

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7. Basic Blu‐ray Disc Characteristics

7.1 Large Recording Capacity

The Blu ray 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.

7.2 High Speed

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

7.3 Resistant to Scratches and Fingerprints

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

8. Blu-ray Founders

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The Blu-ray Disc is a technology platform that can store sound and video while

maintaining high quality and 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 following companies have jointly established the basic specifications Blu‐ray disc video recording format

1. Hitachi, Ltd

2. LG Electronics Inc.

3. Matsushita Electric Industrial Co. Ltd.

4. Mitsubishi Electric Corporation

5. Pioneer Corporation

6. Royal Philips Electronics

7. Samsung Electronics Co. Ltd.

8. Sharp Corporation

9. Sony Corporation

10.Thomson

9. Characteristics of Ideal Communication

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1. Speed: The blue laser technology will allow DVD recording devices to

record data at a speed of 36Mbps. Developing companies such a TDK also

stated that they will be able to increase the recording speed up to 72Mbps

and 144Mbps. Developing companies such as Toshiba 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

reliable backup at affordable prices. Media types will provide a 50 year data

life. They will also employ a new dual shutter cartridge to minimize

contamination and protect valuable data stored on a disc.

3. Quality: Media storage devices using this technology will have a quality

similar to the quality 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 discs which can cause data on a disc to be

unreadable. Laser printers would me more precise than regular 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 use them. 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 of an optical disc recording device using blue ray will start

off with a high price tag around $1700. Just like any computer related devices

that are new the price will decrease as time passes. It has a high storage

capacity which is up to 60 GB on a dual sided DVD.

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6. Safety and Security: Blue laser light helps in detecting some

chemical and biological 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.

10. How does Blu-ray disc work?

History of Technology

The challenge to write more information on disk Shiju Nakamura is credited

with inventing 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 have a wavelength of around 650 nanometers and are used for

reading and writing DVD and CD discs. The shorter wavelength means that the

laser can register smaller dots on a disc and more data can be stored. As a

result, blue laser technology has been adopted for the development 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.

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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 the optical disc and the way the laser is applied to the disc, in the

size of the pits the laser makes on an optical disc.

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

with smaller pit sizes.

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11. Comparisons

While current optical disc technologies such as CD, DVD, DVD-R, DVD+R, DVD-

RW and DVD+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 the laser beam with even

greater precision. This allows data to be packed more tightly on the disc and

makes it possible to fit more data on the same size disc. Despite the different

type of lasers used, Blu-ray Disc Recorders will be made compatible with

current red-laser technologies and allow playback of CDs and DVDs.The

following diagram shows the comparison between different storage Techn.

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12. Blu-ray Disc and HD-DVD

The HD DVD format, originally called AOD or Advanced Optical Disc, is based ‐on much of today’s DVD principles and as a result, suffers from many of its limitations. The format does not provide as big of a technological step as Blu‐ray Disc. For example, its pre recorded capacities are only 15 GB for a single ‐layer disc, or 30 GB for a double layer disc. Blu ray Disc provides 67% more ‐capacity per layer at 25 GB for a single layer and 50GB for a double layer disc.

Although the HD DVD format claims it keeps initial investments for disc ‐replicates and media manufacturers as low as possible, they still need to make substantial investments in modifying their production equipment to create HD‐DVDs. But what’s more important is that HD DVD 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 with bonus material in HD quality and additional material that can be revealed upon authorization via a network. When two discs are needed, this will degrade the so called cost benefit substantially. It is even possible that the HD DVD ‐ ‐specification will be followed up by a renewed version of the technology within a few years, requiring media manufacturers to upgrade their existing production lines again, and consumers to replace their existing playback/recording equipment. On the other hand, the Blu ray Disc format ‐was designed to be a viable technology for a period of at least 10 to 15 years.

Also on the application layer, the HD DVD format incorporates many ‐compromises. As the capacity is not likely to be sufficient to encode a full‐length feature plus additional bonus materials using the MPEG 2 format, ‐different and stronger encoding formats need to be used. Although Blu ray ‐Disc offers these advanced codec as well, the disc has such high capacity that publishers can still use the MPEG 2 encoding format at bit rates up to 54 ‐Mbit/sec. As MPEG 2 is the de facto standard used in almost any industry ‐ ‐involved in digital video (DVD, HDTV, digital broadcast), many authoring solutions are available. Chances are high that a full line MPEG 2 encoding suite‐ is already available, which can be used with no or minor adaptations to encode High Definition content for Blu ray Disc. But perhaps the most important factor‐ for the success of Blu ray Disc is its overwhelming industry wide support. ‐ ‐Almost all consumer electronics companies in the world (combined market share of about 90%) and the world’s two largest computer companies support the Blu ray Disc format.‐This ensures a large selection of Blu ray Disc players, recorders, PC drives,‐

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Blu ray Disc equipped PCs and blank media will become available. A competing‐ format will not have the manufacturing power to penetrate the market in a level even approaching that of Blu ray Disc.‐

13. Advantages

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The main advantages of the Blu ray disc are‐

More storage capacity on a disc of the same size

The data storage capacity on a Blu ray disc is 27GB on a single layer and 54GB ‐on dual layer, 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 Blu ray disc is about 36Mbps which is about ‐three times that of a DVD and thirty times that of a CD.

Available in different versions like ROM, R and RE

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 equally well 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.

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• Renewability with Renewal Key Block and Device Key.

• Enhanced Encryption Algorithm: AES 128 bit.

• Physical Hook against Bit by Bit Encrypted Content Copy.

• Title based 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 the recording 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

In the case of ordinary discs, the disc life is less fir the rewritable versions, as re writing is done repeatedly to one area of the disc most probably, the inner ‐perimeter. This limits the disc life. But, the BDFS(Blu ray Disc File Structure is ‐designed so as to avoid this problem, by using a system that uses free disc spaces with equal frequency.

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14. The Blu-ray Impact

Blu-ray is expected to challenge DVD's run as the fastest selling consumer-

electronics item in history. If that happens, the impact would be too big for the

major players to discount. For example, the number of films sold on DVD more

than doubled last year to over 37 million. In addition, almost 2.4 million DVD

players were bought in the past year. As Blu-ray is not compatible with DVD,

its success could upset the applecart of many players. If the new format turns

out to be much popular, the demand for DVD players could come down

drastically. Not withstanding the challenge to DVD makers, the new format is

seen as a big step in the quest for systems offering higher data storage. It is

expected to open up new opportunities for broadcasting industry. Recording

of high-definition television video—an application in which more than 10GB of

storage space is filled up with just one hour of video—will get a major boost.

Conversely, the format could take advantage of the spread of high-definition

television. As Blu-ray Disc uses MPEG-2 Transport Stream compression

technology, recording for digital broadcasting would become easier. Its

adoption will grow in the broadband era as it offers a technology platform to

manage stored content. But the real action will begin when the companies

involved develop products that take full advantage of Blu-ray Disc's large

capacity and high-speed data transfer rate. As that happens, Blu-ray will move

beyond being a recording tool to a variety of applications. Adoption of Blu-ray

Disc in PC data storage is already being considered.

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15. Applications

High Definition Television Recording

High Definition Video Distribution

High Definition Camcorder Archiving

Mass Data Storage

Digital Asset Management and Professional Storage

The Blu ray 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 format‐ ’s versatile design and top of the line specifications mean that it is‐ ‐ ‐ suitable for a full range of other purposes as well.

15.1 High Definition Television Recording

High Definition broadcasting is vastly expanding in the US and Asia. Consumers are increasingly making the switch to HDTV sets to enjoy the best possible television experience. The Blu ray Disc format offers consumers the ability to ‐record their High Definition television broadcasts in their original quality for the first time, preserving the pure picture and audio level as offered by the broadcaster. As such it will become the next level in home entertainment, offering an unsurpassed user experience. And since the Blu ray Disc format ‐incorporates the strongest copy protection algorithms of any format or proposal to date, the format allows for recording of digital broadcasts while meeting the content protection demands of the broadcast industry.

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15.2 High Definition Video Distribution

Due to its enormous data capacity of 25 to 50 GB per (single sided) disc, the Blu ray Disc format can store High Definition video in the highest possible ‐quality. Because of the huge capacity of the disc, there is no need to compromise on picture quality. Depending on the encoding method, there is room for more than seven hours of the highest HD quality video. There is even room for additional content such as special features and other bonus material to accompany the High Definition movie.

Furthermore, the Blu ray Disc movie format greatly expands on traditional‐DVD capabilities, by incorporating many new interactive features allowingcontent providers to offer an even more incredible experience to consumers.An Internet connection may even be used to unlock additional material that is‐stored on the disc, as there is enough room on the disc to include premiummaterial as well.

15.3 High Definition Camcorder Archiving

As the market penetration of High Definition TV sets continues to grow, so does the demand of consumers to create their own HD recordings. With the advent of the first HD camcorders, consumers can now for the first time record their own home movies in a quality level unlike any before. As these camcorders are tape based, consumers cannot benefit from the convenience ‐and direct access features they are used to from the DVD players and recorders. Now, the Blu ray Disc format, with its unprecedented storage ‐capacity, allows for the HD video recorded with an HD camcorder to be seamlessly transferred to a Blu ray Disc. When the HD content is stored on a ‐Blu ray Disc, it can be randomly accessed in a way comparable to DVD. ‐Furthermore, the Blu ray Disc can be edited, enhanced with interactive menus ‐for an even increased user experience and the disc can be safely stored for many years, without the risk of tape wear.

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15.4 Mass Data Storage

In its day, CD R/RW meant a huge increase in storage capacity compared to ‐traditional storage 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 e mail and the migration to paperless processes. The ‐Blu ray Disc format again offers 5 to 10 times as much capacity as traditional ‐DVD resulting in 25 to 50 GB of data to be stored on a single rewritable or recordable disc. As Blu ray Disc uses the same form factor as CD and DVD, this ‐allows for Blu ray Disc drives that can still read and write to CD and DVD media‐ as well.

15.5 Digital Asset Management and Professional Storage

Due to its high capacity, low cost per GB and extremely versatile ways of transferring data from one device to another (because of Blu ray Disc‐ ’s extremely wide adoption across the industry), the format is optimized for Digital Asset Management and other professional applications that require vast amounts of storage space. Think of medical archives that may contain numerous diagnostic scans in the highest resolution, or catalogs of audio visual assets that need to be instantly retrieved in a random access manner, without the need to “restore “ data from a storage carrier. One Blu ray Disc may ‐replace many backup tapes, CDs, DVDs or other less common or proprietary storage media. And contrary to network solutions, the discs can be physically stored in a different location for backup and safekeeping.

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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 players available in the market is very high.

HD-DVD

The HD DVD (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 storage density is lower, it has lower manufacturing costs also, which may prove challenging to the Blu ray disc.‐

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18. Future Developments

Efforts are progressing on many fronts to make the Blu ray discs, players and ‐recorders cheaper. On 15 April 2004 for instance, Sony and Toppan Printing announced the successful development of a Bluray Disc that is 51% (by mass) composed of paper, which could reduce production costs and improve its environmental friendliness. The cost would come down 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 UV‐curable resin is being used for the researches and results are encouraging.

Figure shows the cross section of the disc being developed.

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19. Conclusion

In conclusion the Blue-ray Disc is a technology platform that can store sound

and video while 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 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.

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20. REFERENCES

Research Papers:

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. Dürig, B. Gotsmann, W. Häberle, M. A.

Lantz, H. E. Rothuizen, R. Stutz, and G. K. Binnig:

3) “34 GB Multilevel-enabled Rewritable System using Blue Laser and High

NA Optics”. By H. Hieslmair, J. Stinebaugh, T. Wong, M. O’Neill, M. Kuijper, G.

Langereis: Published at ISOM/ODS Hawaiï, July 2002.

Websites:

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

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

http://www.bluraydisc.com/

http://www.blu-raytalk.com/

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