BLU-RAY DISC TECHNOLOGY: A VRITABLE OPTICAL MEDIUM FOR SECONDARY
DATA STORAGE (A SURVEY, ANALYSIS AND APPLICATION)
BY
AKINDE, O. K., OPARA, F. K., and ETUS C.,
Department of Electrical and Electronic Engineering Technology, FUTO, Nigeria.
ABSTRACT
High-definition (HD) consumer video-electronics equipment is being introduced in increasing
quantities into the world market in these few years. An important aspect of HD is the availability of
suitable storage media and systems. Research has revealed that leading manufacturers around the
world are focusing on the innovative Blu-ray Disc standard is a potential low-cost answer to this need.
The goal of this paper is the review of this currently reigning storage media which has virtually caught
the attention of home, office, business and entertainment domain. The development technique,
especially the use of the novel blue (violet) laser diode with shorter wavelength to achieve a ultracompression of video, audio and computer data streams are significant area the work was focused.
Superiority of Blu-Ray Disc especially in terms of efficient high capacity storage media, easier and
cheaper to produce, couple with affordability and portability are quite laudable and desirable. These
indexes were x-rayed with the comparative analysis of BD with other existing and the yet unborn ones.
Blu-Ray technology is gaining more and more popularity and acceptance in today's worldwide
operations.
Keywords:
Polycarbonate, amorphous state, wobbled groove, Pitch, Blu-ray discs, DRM, UDO.
1.0 INTRODUCTION
The need for high definition optical media increases at alarming rate for the home, office,
business and entertainment environment. This inevitable need informs the drive behind the current and
constant technological advancement in the development and the design of more versatile and
accommodating memory storage devices. The crave for a high compression of High Definition (HD)
content of video, audio, and data onto a single or dual layer disc has resulted in the discovery of the
veritable Blu-ray technology; and this consequently lead to the production of Blu-ray Disc (BD).
Etymologically, Blu-ray acronym is derived from two words- "blue" and "ray". The "blue"
stand for the color of the laser that is used, and "ray," for optical ray. The "e" in "blue" was
purposefully left off because an everyday word cannot be trademarked [David, 2006]. Blu-ray Disc
(also known as Blu-ray or BD) is an optical storage medium. Blu-Ray was created to store larger
amounts of high definition video, sound and data storage. The disc has the same physical dimensions
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as standard DVDs and CDs. Blu-Ray technology is so-named because of its use of blue laser
technology in storing and reading data onto the disc. Being on the shorter wavelength end of the light
spectrum than the red laser used for DVD and CD technologies (405 nanometer for Blu-Ray versus
650 nanometer and 780 nanometer for DVD and CD technology), blue laser is capable of storing a
much larger amount of data using the same space because of a much smaller "spot size" requirement.
Blu-Ray's 405nm wavelength blue-violet laser uses a 0.85nm pickup aperture. In part because of the
shorter wavelength (405 nanometres), substantially more data can be stored on a Blu-ray Disc than on
a DVD, which uses a red (650 nm) laser. [Blu-ray Disc Association, 2008], [Tech-FAQ, 2008].
Blu-ray is the next-generation digital video disc. It can record, store and play back highdefinition video and digital audio, as well as, computer data. The advantage of Blu-ray is the sheer
amount of information it can hold: A single-layer Blu-ray disc, which is roughly the same size as a
DVD, can hold up to 25 GB of data that's more than two hours of high definition video or about 13
hours of standard video. A double-layer Blu-ray disc can store up to 50 GB, enough to hold about 4.5
hours of high-definition video or more than 20 hours of standard video. Besides, there are on-going
researches and plans to develop a disc with twice that amount of storage [Randy, 2009]
1.1 Historical Background of Blu-ray
In 1983, compact disc (CD) technology was introduced into the United States revolutionizing
the music and movie industries. Both music and movies benefited from the switch to digital which
provided great clarity and storage space. “CD quality sound” became the catch phrase to denote quality
music recording. As the industry grew, demand increased for better picture quality which meant
greater storage capacity. Digital Versatile Disc (DVD) was introduced to meet this need and was met
with great success [Chen An Huang, Yizhou Liu, Zhizhang Xia, 2006].
Actually, Blu-Ray technology is the next step in the evolution of media formats. To understand
it better, one must understand the formats prior to blu-ray and why there was a need for blu-ray. By
evaluating CD and DVD technology, it will be easier to understand the improvements blu-ray
technology brings. Compact Discs (CD) first came to market in 1982, and still remains the main
medium type on which to store music. CD technology was the first “optical disc” technology that
reached widespread acceptance. Laser discs had come before it but had not been widely accepted. A
standard CD is 120mm in diameter, can hold around 80 minutes of audio or 700MB of data, is 1.2mm
thick, and weighs approximately 16 grams. A CD is made of four layers [Randy, 2009]; these include a
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polycarbonate disc layer where the data is stored, a reflective layer which reflects the laser light back, a
lacquer layer to prevent oxidation, and an artwork layer, screen printed to the top of the CD.
The data is transferred as a series of “pits” and “lands” on the polycarbonate layer of the CD.
These pits and lands are a representation of binary data. A transition from a pit to a land or from a land
to a pit translates as a one (true) whereas a continuation of a pit or land signifies a zero (false).
CD technology was updated with the release of the “Digital Versatile Disc”, or DVD. DVD is
actually the cojoined efforts of two previous technologies, Super density (SD) disc and MultiMedia
Compact Disc (MMCD). Rather than participating in a format war, the originators of these two
technologies were brought together to agree upon one standard. DVD was the result. DVD’s main
advantage over CD technology is the amount of data the disks can hold. A single-layer, single-sided
DVD holds approximately six times the amount of data that a CD holds [Microsoft Encarta, 2009].
DVDs can be dual-layer, which gives them roughly double capacity as a single-layer disk. They can
also be double-sided.
DVDs used in commercial movie distribution are typically single-sided, dual layer disks. This
allows for up to two hours of standard definition video/audio and extra features such as commentary
and games. DVDs were great as a video medium for many years, but there came a need for higher
definition video. Larger screens helped show the lack of quality in standard definition DVD videos.
HDTVs started to become more popular, but HDTVs are not very useful unless one has high definition
content to play on them. A new type of media was needed. DVD technology wasn’t sufficient enough
to store the amount of data needed for standard length high definition audio/video. Two new
technologies were developed to replace DVD, HD-DVD and Blu-Ray [Randy, 2009]
Now in 2007, the Sony Blu-Ray emerged as the new standard to take over the next generation
of media disc. Philips and Sony started two projects applying the newly discovered diodes (blue) laser.
Ultra Density Optical (UDO) and DVR Blue (together with Pioneer), forms the format for rewritable
discs which would eventually become Blu-ray Disc (more specifically, BD-RE). The core technologies
of the formats are essentially similar. The first DVR Blue prototypes were unveiled at the CEATEC
exhibition in October 2000 [Luitjens, 2001, Martyn, 2002]. Because the Blu-ray Disc standard places
the data recording layer close to the surface of the disc, early discs were susceptible to contamination
and scratches and had to be enclosed in plastic cartridges for protection. On February 19, 2002, the
project was officially announced as Blu-ray, and the Blu-ray Disc Founders was founded by the nine
initial members [Barry, 2002]. This device was the Sony BDZ-S77; a BD-RE recorder then was made
available only in Japan. Then there was no standard for pre-recorded video and no movies were
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released for this player. The Blu-ray Disc standard was still years away as a newer, more secure digital
right management (DRM) system was needed before Hollywood studios would accept it, not wanting
to repeat the failure of the Content Scramble System used on DVDs. On October 4, 2004, the Blu-ray
Disc Founders was officially changed to the Blu-ray Disc Association (BDA) and 20th Century Fox
joined the BDA's Board of Directors [Blu-ray founders, 2004].
1.2 The Technology Underlining Blu-ray Disc (BD) Production.
What was gigabyte (GB) in the early 1990s is terabytes (TB) today and will be petabyte (PB)
within the next 30 years as the demand from home digital applications accelerates.
Figure 1: A Forecast of home digital information growth
At the end of the 1990s, when DVD just left the status of development technology, leaders like
Sony and Philips started to think about the next generation of optical data storage. The target for the
storage capacity was high-definition digital television (HDTV) technology requiring a capacity of 30
GByte per disk and a data transfer rate of 30 – 40Mbit/s. This improvement by a factor of 6 – 7 with
respect to DVD was only achievable, when the laser wavelength and therefore the size of the structures
on the disk could be reduced substantially.
According to the correlation: D
0.6 λ x / NA, the diameter of the laser focus (FWHM) is
proportional to the wavelength(λ) and inversely proportional to the numerical aperture of the optical
system. A violet laser around 400 nm therefore could reduce the focus by 1.6 with respect to DVD
(650 nm) increasing the storage capacity by a factor of 1.62 to 2.6. First attempt was made towards
violet emitting semiconductor materials like gallium-nitride or zincselenide. In 1999, the Japanese
chemical manufacturer, Nichia was able to offer the first 5mW laser diodes at 405nm using GaN. It
was developed under the scientific leadership of S. Nakamura [Thomas, 2004]
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The technology employed in the production of Blu-ray Disc is quite distinct and unique. An
optical pick-up technique is used in transmitting video, audio, or information unto the BD layer. The
Blu-ray Disc (BD) system uses blue light and a high numerical aperture (NA) of 0.85. A cover layer
thickness of 0.1 mm is chosen to secure sufficient disk tilt margin [Maxim, 2007].
The way a ‘Blu-ray’ disc is made is important because it should be the first disc that is
environmentally friendly. The substrate that keeps the disc together is made out of paper, which makes
up 51% of the disc. The recording layer lays under a 0.1mm protective layer and on top the 1.1mm thick
substrate [Digitmak, 2004]. CD and DVD substrate is usually made from polycarbonate plastic; even
‘HD DVD’ uses it. The paper with which ‘Blu-ray’ disk is made can be cut up easily getting rid of
unwanted data and recycled. This will help to dispose of unwanted Cd’s that come free with newspapers
and magazines. Like ‘HD DVD’, the ‘Blu-ray’ disc players use blue/violet lasers to read and write the
disc. This is where it gets its name. The size of the laser is only 405 nanometres wide whereas the
conventional red laser for CD and DVD is 650 nanometres wide [Toshiba, 2008]. On a DVD, the
minimum pit length, which is a segment of information, is 0.4 nm whereas ‘Blu-rays’ is much smaller.
The track pitch on which the pits lie, similar to record grooves, is also only 0.32nm compared to DVD
which is 0.74nm apart.
Figure 2: A cross section that shows the differences between DVD and ‘Blu-ray’ disc.
The next part is the recording layer where the information is written, stored and read. The
recording layer works no differently to a DVD. A single layered disc will be burnt with a laser that
burns at 4 to 11 mW. Burning the recording layer creates a pit were the information is held; the laser
burns the layer at 220oC [webelements, 2005]. BD layer is made of a mixture of four different
elements. These are Silver (Ag), Indium (In), Antimony (Sb) and Tellurium (Te). Silver is the most
expensive substance in the whole disk and as such not much is used. It comes in many forms including
crystals that are in the disc. The next is indium, which is metallic. It comes in different states including
a nanosized-activated powder. The third material is Antimony, which again is metallic and has a brittle
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crystalline texture. The final element is Tellurium, which is semi-metallic. It is crystalline and brittle as
well (webelements, 2005). These four elements make up the recording layer and they work when the
laser heats them up. They change their state, to create pits. When they are cooled quickly they keep the
same state. This is called “amorphous state” (See Figure 3) [Jacques H, 2002 ].
Fig 3: Heating and cooling when burning in data;
Fig 4; Heating and cooling as crystals return to original state
However, to write over the data or erase the disc you have to turn the crystals back to their
original state. The crystals must be slowly heated this time, in order to change them back into their
original state. This process is called “polycrystalline state” (Figure 4). This process is called “Phase
change recording” as you are changing the phase and structure of the crystals so they contain different
information [Optical disc magazine, 2002]. The data itself is set in grooves as on a record and this is
what the laser follows when it reads and writes the disc. The crystals are placed around in the grooves.
Next to that is what is called “Pitch” also known as “Land” which is space between the grooves that
separates them and cannot be recorded onto (See figure 5) [Studio systems, 2002].
Figure 5: The grooves, lands and pits on a disc.
1.3 Types of Blu-ray Discs
The following types of Blu-ray disc been have designed and are currently in active use; each of
them are produced via similar technology [Bludisc.com, 2008], [Randy, 2009]:
a.) The '''Mini Blu-ray Disc''' (also, Mini-BD and Mini Blu-ray) is a compact 8cm (~3in) diameter
variant of the Blu-ray Disc that can store approximately 7.5GB of data. It is similar in concept to
the MiniDVD. Recordable (BD-R) and rewritable (BD-RE) versions of Mini Blu-ray Disc have
been developed specifically for compact camcorders and other compact recording devices.
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b.) BD9 and BD5 are lower capacity variants of the Blu-ray Disc that contain Blu-ray compatible
video and audio streams contained on a conventional DVD (650nm wavelength / red laser) optical
disc. Such discs offer the use of the same advanced compression technologies available to Blu-ray
discs (including H.264/MPEG-4 AVC, VC-1 and MPEG-2) while using lower cost legacy media.
c.) AVCREC is an official lower capacity variant of the Blu-ray Disc used for storing Blu-ray
Disc compatible content on conventional DVD discs. It is being promoted for use in camcorders,
distribution of short HD broadcast content and other cost-sensitive distribution needs.
d.) Blu-ray Disc recordable (BD-R) refers to two optical disc formats that can be recorded with
an optical disc recorder. BD-R discs can be written to once, whereas Blu-ray Disc rewritable (BDRE) can be erased and re-recorded multiple times.
1.4 How Blu-ray Works
As earlier stated, the Blu-Ray technology uses a "blue" (technically violet) laser rather than a
red laser (DVD). The shorter wavelength allows Blu-Ray disc to store 25GB of data on each layer
compared with DVD’s 4.7GB [Randy, 2009]. Blu-ray Disc uses a laser operating at a wavelength of
405 nm to read and write data. Conventional DVDs and CDs use red and near infrared lasers at 650 nm
and 780 nm respectively. The blue-violet laser's shorter wavelength makes it possible to store more
information on a 12 cm CD/DVD sized disc. The minimum "spot size" on which a laser can be focused
is limited by diffraction, and depends on the wavelength of the light and the numerical aperture of the
lens used to focus it. By decreasing the wavelength, increasing the numerical aperture from 0.60 to
0.85 and making the cover layer thinner to avoid unwanted optical effects, the laser beam can be
focused to a smaller spot. This allows more information to be stored in the same area. Figure 6
illustrates the typical laser light and its wavelength for BD production.
Figure 6: Laser Emission from a Single unit 3-Wavelength Laser Prototype.
For Blu-ray Disc, the spot size is 580 nm; this enable Blu-ray Discs feature improvements in
data encoding that further increase the capacity [Press Release, 2004]. This means that the pits and dips
will be even closer making the disc hold more information. [Blu-ray founders, 2002].
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2.0 HARD-COATING TECHNOLOGY
Initially, the earlier products of Blu-ray were vulnerable to scratches because the Disc data
layer was closer to the surface of the disc, compared to the DVD standard. Consequently, the first discs
were housed in cartridges for adequate protection. But the Hard-coating technology was later invented,
and then a working scratch protection coating for Blu-ray Discs was used. The organic substance for
the hard coating was named Durabis [Physog.com, 2005]. Also, Sony and Panasonic's replication
methods include proprietary hard-coat technologies. Sony's rewritable media are spin-coated with a
scratch-resistant and antistatic coating [Blu-ray Disc Founders, August 2004]. Verbatim recordable and
rewritable Blu-ray Disc used proprietary hard-coat technology called ScratchGuard.
On August 8, 2008, Buffalo, Japan announced the shipping of the first 8x Blu-ray burners in
September 2008. On September 22, 2008, Buffalo announced the release of one internal and one
external 8x Blu-ray burners for the United States. The following day Sony announced the release of
BWU-300S, an internal 8x Blu-ray burner for the United States [Engadget, 2008].
2.1 Recording speed
A device with optical head is employed to transfer digital information onto the surface of a BD
using a laser with numerical aperture of 0.85. The Disc thickness is 1.2mm with a protective layer of
0.1mm, whereas DVD has a protection of 0.6mm. The substrate of the ‘Blu-ray’ disc will be 1.1mm on
the top with the recording layer on the bottom. All ‘Blu-ray’ discs are re-writeable with 0.85 numerical
apertures, which is the amplitude of the laser (see figure 7). It is a much wider amplitude than the DVD
laser making it more precise. It is also closer to the disc compared to CD where the laser has to go right
to the top to read and write. The recording layer of DVD is in the middle, while that of BD is situated
right at the bottom above the 0.1mm protection.
Figure 7: The 0.85 numerical amplitude of the blue laser.
The table below stipulates the speed at which recording of Blu-ray Disc could be done.
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Table 1: The Recording Speed of Blu-ray Disc.
Data rate
Write time for Blu-ray
Disc (minutes)
Drive speed
Mbits/s
MB/s
Single Layer
Dual Layer
1×
36
4.5
90
180
2×
72
9
45
90
4×
144
18
23
45
6×
216
27
15
30
8×
288
36
12
23
12×
432
54
8
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3.0 TECHNOLOGY STANDARDS, DIGITAL RIGHTS MANAGEMENT, AND FORMAT OF
BLU-RAY DISC.
Standards are established in order to ensure quality control in disk production, as well as, to
enforce laws that govern uniformity among various groups of disc producers.
As an important step in establishing new formats, the company groups define detailed
standards: which contain the physical properties of the disks, the specifications of the disk drives, and
the exact data structure. Only such strict definitions guarantee that every disk can be read back on
every drive – if both are according to the standard. For the disk replicators, which reproduce disk with
highly efficient molding and coating processes the quality assurance is an important and central control
task. As regards quality testing online and offline tests can be distinguished [Thomas Weber, 2004].
The physical specification of BD was finalized in 2004 [Martyn, 2004]; While that BD-ROM
was done in 2006 [Tony, 2006]. A few seconds online process was used to check every disk for its
physical properties during and after manufacturing process; (e.g. substrate defects, substrate thickness,
deformation, and reflectivity); this is referred to as physical test. In the complementary electrical test, it
is checked whether all data can be read back completely and correctly requiring to fully play a random
sample disk on a drive. The time effort makes this test to be performed offline only [Sarah, 2007].
3.1 Digital Rights Management
The BD format employs several layers of digital rights management to ensure BD-ROM
contents’ protection [Ajima, 2006]. Figure 8 is the schematic to ensure content integrity and security.
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AACS
RECORDED MADE WITH AAC DECRYPTION PROCESS
Made Key Block (MKB)
Subtract/ Difference
Tree System
Processing Key (
PK)
AES.G
Encrypted Content
Volume D
DECRYPTION
DECRYPTION
Down Ice Key Frequency Keys
CONTENT
Figure 8: Advanced Access Content System (AAC) Decryption process
The Advanced Access Content System (AACS) is a standard for content distribution and digital
rights management. It was developed by American Standard (AS) Licensing Administrator, LLC
(AACS LA), a consortium that includes Disney, Intel, Microsoft, Matsushita (Panasonic), Warner
Bros., IBM, Toshiba and Sony. Since invention in 2006, several successful attacks have been made on
the BD format. The first known attack relied on the trusted client problem. In addition, decryption keys
have been extracted from a weakly protected player (WinDVD). Since keys can be revoked in newer
releases, this is only a temporary attack and new keys must continually be discovered in order to
decrypt the latest discs. This cat-and-mouse game has gone through several cycles and as of August,
2008 all current AACS decryption keys are available on the Internet [Ajima, 2006], [aacla.com, 2007].
Furthermore on security, Blu-Ray supports mandatory HDCP encrypted output, ROM-Mark
watermarking, BD+ dynamic cryptology, and the Advanced Access Content System (AACS).
The world continent was grouped into three regions for BD production and distribution. Each
region has a unique cod; the regions are: one, countries in the American continent as well as countries
in east Asia except China and Japan; two, countries in the European and African continents; and lastly,
other countries in the Asian continent such as China, Russia, etc [raystats.com, 2008; videohelp.com,
2006]. This ensures that a BD sold in North America is not viewable on BD players used in Europe or
in Asia. With this, the international distribution of motion pictures is assured. And so, the BD of a
movie is not available before that motion picture is officially released in a region.
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3.2 Blu-ray Disc (BD) Formats
Basically, there are three formats being developed for Blu-Ray technology. These are the BD
read-only disc (BD-ROM) or, the BD recordable (BD-R), and the BD rewritable (BD-RE) [Longman,
2002]. BD-ROM will be used to store movies, computer games and software. The BD-R will provide
users the opportunity to store larger amounts of data and HDTV recordings in one disc; while the BDRE format will provide users the ability to change the disc's contents.
Blu-Ray discs are capable of supporting different file formats such as MPEG-2, MPEG-4 High
Profile AVC and VC-1 coder decoders. This enables the discs to store up to four hours worth of HDTV
audio-video per layer. It is also capable of supporting the different multi-channel audio file formats
such as the different file formats of Dolby and DTS. BD rewritable and recordable disc formats will
also be backwards-compatible with older formats such as MPEG-2, while newer codecs will enable
BD technology to support new file formats in the future. The integration of Java cross platform also
enables the Blu-Ray disc to have interactive menus, as well as, the capability to add new content or
updates such as new subtitles through the Internet [Blu-ray Disc Founders, August 2004].
3.3 Disc Capacity
The main advantage of Blu-Ray technology is its capability of storing massive amounts of data
in one disc. Blu-Ray technology will enable users to store an average of 25GB-27GB worth of data
into just one layer. This is equivalent to 4 hours worth of HD video and audio. Moreover, Blu-Ray dual
layer discs will have a storage capacity of up to about 50GB. Research on Blu-Ray discs with up to
four layers and with storage capacities of up to 200 GB is currently underway.
4.0 COMPARATIVE ANALYSIS OF OPTICAL STORAGE MEDIA
Blu-ray Disc [BD] has won the top spot as the successor to DVD [Michael, 2007]. As, it is
compared with the previously developed optical storage media, as well as, with the upcoming but
never ripen technologies; BD, so far, stand out distinctly as a veritable and versatile storage medium in
terms of capacity storage, simplified technology, disk durability, overall production cost, just to state a
few. The analysis of BD with other media is considered as follows:
4.1 Blu-Ray and Magnetic Tape
Magnetic tape and disk drives have to watch out for cut-throat competition as optical disks
offering superior quality emerge as the preferred choice for large storage archives. The increase in area
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densities in optical disks makes them prime candidates for archival storage on account of their
durability and ease of use. Blu-ray, with its high-density capabilities, leads the optical storage pack and
is in pole position to exploit the lucrative archival storage market.
4.2 Blu-Ray Disc, CD and DVD.
At last, there are fundamental drivers defining future capacity and performance requirements
for ‘entertainment-class’ optical disk technology. The ‘perfect-storm’ of home computer,
entertainment, and personal records convergence (movies-TV, photos, music, video, and gaming)
catalyzes a strong market requirement that will provide for a long and healthy future for DVDcompatible storage.
Like ‘HD DVD’, the ‘Blu-ray’ disc players use blue/violet lasers to read and write the disc. The
size of the laser is only 405 nanometres wide whereas the conventional red laser for CD and DVD is
650 nanometres wide. This means the pits and lands will be even closer making the disc hold more
information. On a DVD, the minimum pit length, which is a segment of information, is 0.4 nm whereas
‘Blu-rays’ is much smaller [Martyn, 2002]. The track pitch on which the pits lie, similar to record
grooves, is also only 0.32nm compared to DVD which is 0.74nm apart.
DVD is an optical storage device in the form of a flat plastic platter that has the same diameter
as a compact disc (CD). Originally called a digital video disc, the DVD is able to hold many times the
digital information that can be stored on a CD; but not up to the capacity of BD.
DVDs have been widely adopted for recordings of motion pictures and other video material sold for
home viewing, and for distributing copies of computer software, and interactive video and computer
game software. Other types of material available in digital form on DVDs include multimedia
encyclopedias, high-fidelity audio, and collections of photographs. High-definition DVDs have much
higher storage capacity, permitting high-definition video and a wider variety of interactive features.
Because of the migration path from CD-to-DVD-to-Blu-ray-to-(the next distribution
technology) optical storage does not go away for a long-time. In fact, the opposite appears to be
happening. The DVD-ROM stores computer data. The uses of DVD-ROM include interactive games,
video file storage, and photographic storage; it is called the “digital versatile disc” because it can be
used in a variety of ways. When compared to CD-ROM technology, DVD allows for better graphics,
greater resolution, and increased storage capacity. However, BD uses still surpasses these.
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Figure 9 distinguishes between the optical heads and the disc surface structure of the CD,
DVD, and BD [Longman, 2002]. The finer structure of the BD gives room for its higher capacity of
video and other information compression.
Figure 9: Comparison of optical heads and structure size of CD, DVD and BD disks (courtesy of Philips research)..
4.3 Blu-Ray Disc (BD) and HD-DVD
Competing with BD, the HD-DVD platform is a weak alternative, since BD has cornered the
entertainment distribution media market. Compatibility is essential and a 5-to-10 times jump in
capacity per disk at low cost with read compatibility is really something.
Blu-ray disc (BD) is a form of High-definition DVDs (HD-DVD). HD DVDs were developed
in two incompatible formats: Blu-ray and HD-DVD. The HD-DVD technology was later abandoned by
manufacturers; it gives way to Blu-ray disc. A single-layer Blu-ray disc has higher-density storage than
a single-layer HD-DVD. Blu-ray technology permits dual layers to increase data storage capacity.
Although both Blu-ray and HD-DVD are similar in many aspects, there are some important
differences between them [Longman, 2002].
✓ The first is capacity. Because BD utilizes a lens with a greater numerical aperture (NA) than HDDVD, the laser spot can be focused with greater precision to fit more data on the same size disc.
This allows BD to hold 25GB per layer (50GB on a dual-layer disc), whereas HD-DVD can only
hold 15GB per layer (30GB on a dual-layer disc). BD has also adopted a higher data transfer rate
for video and audio (54Mbps vs 36.55Mbps). The greater capacity and data transfer rates for BD
will allow the movie studios to release their movies with higher quality than the HD-DVD format.
✓ The second is content. The Blu-ray format has received broad support from the major movie
studios as a successor to today's DVD format. Seven of the eight major movie studios (Warner,
Paramount, Fox, Disney, Sony, MGM and Lionsgate) have already announced titles for BD,
whereas HD-DVD only has support from three major movie studios (Warner, Paramount and
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Universal). This is an important difference because some of the studios might only support one of
the formats, so you won't be able to get your favorite movies in the other format. Choosing the
format with the most content support minimizes this risk.
✓ The third is hardware support. The Blu-ray format has broad support from the world's leading
consumer electronics, personal computer and media manufacturers, including Sony, Panasonic,
Philips, Samsung, Pioneer, Sharp, JVC, Hitachi, Mitsubishi, TDK, Thomson, LG, Apple, HP and
Dell.
The BD format will also be supported in the next generation PlayStation 3 (PS3) video game
console. This means that you will have a lot of choice when it comes to players and hardware. The
HD-DVD format has far less supporters, so the amount of players and hardware will be very limited.
According to Singulus Technologies AG, BD is being adopted faster than the DVD format at
the same period of its development. This conclusion was based on the fact that Singulus Technologies
has received orders for 21 BD dual-layer machines during the first quarter of 2008, while 17 DVD
machines of this type were made in the same period in 1997 [InfoNIAC, 2008]. According to GfK
Retail and Technology, in the first week of November 2008, sales of BD recorders surpassed DVD’s in
Japan [xbitlabs, 2008]. According to the Digital Entertainment Group the total number of BD playback
devices (both set-top box and game console) had reached 9.6 million by the end of 2008. According to
Swicker & Associates BD software sales in the United States and Canada were 1.2 million in 2006,
19.2 million in 2007, and 82.4 million in 2008 [storagenewsletter, 2009].
4.4 Blu-Ray Disc (BD) and Other Optical Media
Early in 2002, an Industry consortium announced a new technology for the consumer market
called ‘Blu-Ray’ which is in essence a new generation of storage products aimed primarily at HD TV
recording. This technology was formerly referred to as DVR and a large number of papers describing
the principles have been published over the last two years.
Blu-Ray technology forms the basis for many of the UDO specification items. Blu-Ray will use
405nm lasers with 100-micron cover layer technology and phase change recording films to deliver
approximately 25 GB on a single CD sized surface. The use of a 0.85 NA lens is the significant area in
which UDO differs from Blu-Ray. Presently, UDO makes use of 0.65NA lens. [Longman, 2002]
Holographic technology drives are now in early stages of production in large shelf-sized
‘canister-like’ boxes with 300GB as the 1st generation disk capacity and a $15,000 price tag.
Holographic technology writes 3-dimensionally as well, utilizing the depth of the media to record a
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digital holographic image which can then be read by recreating the laser hologram [Michael, 2007].
Unfortunately, holographic technology does not use standard DVD-sized media and the media requires
a cover just like magneto-optical media.
Table 2:
Summary Table for different Optical Media
PARAMETERS
BD-ROM
UDO
HD-DVD
DVD-ROM
Storage capacity (single-layer)
25GB
15GB
15GB
4.7GB
Storage capacity (dual-layer)
50GB
30GB
30GB
9.4GB
Laser wavelength
405nm
405nm
405nm
650nm
780nm
Numerical aperture (NA)
0.85
0.7
0.65
0.60
0.45
Protection layer
0.1mm
0.6
0.6mm
0.6mm
1.2mm
Data transfer rate (1x)
36Mbps
32Mbps
25Mbps
7Mbps
210
100
Tilt Sensitivity
80
MPEG-2 MPEG-4
AVC,SMPTEVC-1
Video compression
Manufacturing Process
New
Material Disc is Made from
CD
MPEG-2
New
Paper
DVD like
Pcarbona
Polycarbonat
Polycarbon
5.0 ADVANCES, APPLICATION AND FUTURE PROSPECT OF BLU- RAY TECHNOLOGY
Blu-ray DVD effectively owns the emerging market for high definition (HD)-TV, HD-class
movie distribution. BD will become the platform of choice for many high capacity applications
including personal records preservation system’s back-up. Any new technology that wants to compete
must now be compatible with Blu-ray.
5.1 Advances In Blu- Ray Technology
Although the Blu-ray Disc specification has been finalized, engineers continue working to
advance the technology. Quad-layer (100 GB) discs have been demonstrated on a drive with modified
optics (TDK version) and standard unaltered optics ("Hitachi used a standard drive.")[tdk, 2005].
Hitachi stated that such a disc could be used to store 7 hours of 32 Mbit/s video (HDTV) or 3.5 hours
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of 64 Mbit/s video (Cinema 4K). In August 2006, TDK announced that they have created a working
experimental BD capable of holding 200 GB of data on a single side, using six 33 GB data layers [tdk,
2006].
Figure 10: The Front of an Experimental 200GB Eewritable Blu-ray Disc
Also behind closed doors at CES 2007, Ritek revealed that they had successfully developed a
High Definition optical disc process that extends the disc capacity to 10 layers. That increases the
capacity of the discs to 250 GB. However, they noted that the major obstacle is that current reader and
writer technology does not support the additional layers [Yam, 2007].
JVC developed a three-layer technology that allows putting both standard-definition DVD data
and HD data on a BD/DVD combo. If successfully commercialized, this would enable the consumer to
purchase a disc which could be played on current DVD players, and reveal its HD version when played
on a new BD player. The first 'hybrid' BD/DVD combo is announced to be released February 18. 'Code
Blue' will feature four hybrid discs, which feature a single BlD (25GB) and two DVD layers (9 GB) on
the same side of the disc [nikkeibp, 2009].
In January 2007, Hitachi showcased a 100 GB Blu-ray Disc, which consists of four layers
containing 25 GB each [nikkeibp, 2008]. Unlike TDK and Panasonic's 100 GB discs, they claim this
disc is readable on standard BD drives that are currently in circulation, and it is believed that a
firmware update is the only requirement to make it readable to current players and drives.
In December 2008, Pioneer Corporation unveiled a 400 GB Blu-ray disc, which contains 16
data layers, 25 GB each, and will be compatible with current players after a firmware update. A
planned launch is in the 2009-2010 time frames for ROM and 2010-2013 for rewritable discs. Ongoing
development is under way to create a 1TB Blu-ray disc as soon as 2013 [digitimes, 2008].
5.2 Applications of Blu- Ray Technology
Blu-ray Disc (also known as Blu-ray or BD) is an optical storage medium. Its main uses are
high-definition video and data storage [Wikimania, 2009]. BD has a high-speed 36Mega bit per second
connection, which implies that it can deliver a very high quality picture at the same time as recording.
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In 1995, the world laughed at the idea of a terabyte on the desktop. Notebook PCs were just
pushing 20GB and tape owned movie distribution. Just ten years later, the world gasped at the
recognition of the terabytes we have at home due to the convergence of home digital technologies such
as DVD and HD movies, digital music (CDs, iPods, mp3s), photography, and video. Just add up what
you have at home, terabytes of storage is all around us. Think on what will happen as the digital-home
unfolds. Every appliance, utility, and consumable will have intelligence and will be interconnected. All
of them will be monitoring and collecting data which will be centralized and controlled. For example,
what will be the storage requirements for the digital refrigerator that automatically inventories the food
added or removed based on RFIDs and communicates with the grocery store to maintain its inventory
levels at some threshold synchronized with your household schedules, budgets, preferences, and online
banking [Michael, 2007]. It is getting easier to see how over the next 20-30 years the home’s
information infrastructure will consume and store petabytes of data.
The Blu-ray Disc recorder represents a major leap forward in video recording technology as it
enables recording of high-definition television (HDTV). It will also offer a lot of new innovative
features not possible with a traditional VCR [Longman, 2002], some of these are:
▪
▪
▪
▪
▪
▪
▪
▪
▪
Random access, instantly jump to any spot on the disc;
Searching, quickly browse and preview recorded programs in real-time;
Create playlists, change the order of recorded programs and edit recorded video;
Automatically find an empty space to avoid recording over programs;
Simultaneous recording and playback of video (enables Time slip/Chasing playback);
Enhanced interactivity, enables more advanced applications and games;
Broadband enabled, access online content, download subtitles and extras;
Improved picture, ability to record high-definition television (HDTV);
Improved sound, ability to record surround sound (Dolby Digital, DTS, etc.).
High-definition DVDs are mainly designed for use with high-definition television technology
and have more than three times the data storage capacity of standard DVDs. High-definition DVDs can
also be used for electronic games, permitting enhanced interactivity and media. However a single-layer
Blu-ray disc has higher-density storage than a single-layer HD-DVD. Blu-ray technology permits dual
layers to increase data storage capacity [Microsoft Encarta, 2009]. Samples of these ranges across
home infrastructure, digital entertainment, digital offices and services, legal and compliance record
storage, libraries and Museums, and too many other services oriented and data acquisition practices.
Secure, long-term archival storage is a major consumer of optical disk technology today and this need
is only accelerating.
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5.3 Future Prospect of Blu- Ray Technology
What technologies are going to serve these huge and important storage markets? Clearly, the
technology that is the preferred entertainment distribution media will have the major role. The myth
that all services can be centralized over the internet is just that, a myth. The bandwidth demands are
too great. And, will we trust a central service bureau to retain all of our priceless home and personal
photo, music, movie, or video assets or will most people want them local, secure, and under their
control? In the end, a high capacity removable media will still be required and Blu-ray, DVD and its
successors are viable candidates for these roles.
Here is the point. The storage technologies will dominate the high-capacity digital home and
the enterprise archive of the future: local disk arrays, high capacity ‘entertainment-class’ optical disk,
and centralized service bureaus with storage services. Each has a viable role and each is
complimentary [Thomas, 2004].
The Blu-Ray disc recorder market is now beginning to come into its own, and further
expansion is expected in the future. While the previous recordable Blu-Ray disc (hereafter called BDR） used an inorganic recording layer, adoption of the BD-R LTH Type standard in March 2007
opened the way for use of organic dye materials in the BD-R recording layer [Taiyo, 2008].
Taiyo Yuden has been participating in the standardization of the BD-R LTH Type, utilizing its
design and development technologies for organic dye optical recording discs that the company built up
for CD-R and DVD-R. The company also applied its mass production technology developed for
organic dye optical recording discs for successful mass production of the BD-R LTH Type that upheld
both high-density recording and stable recording quality.
As earlier stated, Blu-ray DVD has won the top spot as the successor to DVD. Just like DVD,
the time will come when Blu-ray is at the top of its lifecycle and the applications will demand higher
capacity and performance. What will be next? History says, leapfrog to a completely new technology
will not win. Blu-ray DVD (and the competing format HD-DVD) technologies are planned to reach the
200GB threshold on their 4th generation based on multilayer recording and then take a jump up to
500GB per disk when blue-violet laser technology becomes available.
In the future, the number of parts and size of the prototype optical head can be reduced by
combining, for example, Optical Lenses and so on. It is believed that a single 3-wavelength
recording/playback optical head is a key to the expansion of BD markets [Blu-ray Disc Founders,
2004].
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BLU-RAY DISC TECHNOLOGY.
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6.0 CONCLUSION
The preservation of the present via appropriate documentary media is an indispensable legacy
for the future, especially, for the unborn ones (or the next generation). So, development-based
researches for a more durable, high capacity and secure storage media are worthwhile effort which will
yield maximal proceeds in the days ahead.
Blu-Ray technology employed the novel blue (violet) laser with its powerful and shorter
wavelength of ultra modern optical technique to deliver a family of veritable and high capacity data
storage products. This ensures that products could be delivered according to specified standard, as well
as, on time and to budget. Later generations push the technology further as the industry develops the
techniques required to manufacture components required to an acceptable level. It seems that the future
holds a whole lot more than 25 to 54 GB on a single disc [Randy, 2009].
When last time was backup exciting? It is now. And being a random-access medium likes a
hard disk, Blu-ray seems fit to displace streaming tape as the most convenient high-capacity backup
option [Alpha Micro, 2007]. Therefore, Blu-ray must establish itself as the format of choice before the
emergence of alternative technologies intended for large capacity applications. Although the upcoming
technologies are still in embryonic stages of development, Blu-ray needs to establish itself fast in the
mass market before the feasibility of a more advanced technology is proven [researchandmarkets.com].
Once consumers have the option to switch over to another storage format, Blu-ray is likely to find it
increasingly difficult to carve a niche for itself.
6.1 Recommendation for BD Better Future
Currently, prices are extremely steep, with the Sony Blu-ray DVD recorder available at $4,000.
This is incredibly high compared to generic DVD recorders that sell for a minimum of $100. Once the
cost of production is reduced, the pent-up demand for high definition content will ensure that Blu-ray
gains access to the mass market. Now it is time to bring this proven technology to market.
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Academic Background of Researchers
Akinde, O. K. is a master’s degree student of Electrical and Electronic Engineering from Federal
University of Technology Owerri (FUTO); and a major in Electronics and Computer Engineering. He
is a researcher on Electronic and Computer related subject matters.
E-mail: solkinde@yahoo.com
Opara, F. K. is a post doctoral candidate of Electronic and Computer Engineering, Federal University
of Technology Owerri, Nigeria. He has researched and published papers in Data Communication
protocols, Channels and Networks. Others are in Computer architecture and management. He is a
member of IEEE from zone 9.
E-mail: kefelop@yahoo.com
Etus, C. is a master’s degree student of Electrical and Electronic Engineering from Federal University
of Technology Owerri (FUTO); and a major in Electronics and Computer Engineering. He is a
researcher on Electronic and Computer related subject matters.
E-mail: etuscw@yahoo.com
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[ AUGUST, 2009.]