Blu ray technology


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Blue Ray Technology is one of the most advancing technologis in the IT sector.

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Blu ray technology

  2. 2. Contents  What is Blu Ray Technology?  Background of Blu-ray Disc Technology  Blue laser precision  The Blu-ray Disc recording layer  Disc manufacturing  Drive compatibility  CD, DVD, BD : A Comparison  HD – DVD  HD – DVD vs BD  Uses and Necessity
  3. 3. What is Blu Ray technology? • Blu-ray, also known as Blu-ray Disc (BD) is the name of a next-generation optical disc format. The format was developed to enable recording, rewriting and playback of high-definition television (HDTV). Blu-ray makes it possible to record over 2 hours of HDTV, or more than 13 hours of SDTV on a 27GB disc. There are also plans for higher capacity discs that are expected to hold up to 54GB of data.
  4. 4. Background of BD  The format was developed by the Blu-ray Disc Founders (BDF), a group of eleven leading consumer electronics companies: Hitachi, Ltd. LG Electronics Inc. Matsushita Electric Industrial Co., Ltd. Mitsubishi Electric Corporation Pioneer Corporation Royal Philips Electronics Samsung Electronics Co., Ltd. Sharp Corporation Sony Corporation TDK Corporation Thomson Multimedia In January 2004, the world's two largest PC manufacturers, HP and Dell, were accepted into the group to help further develop the format for PC data storage.
  5. 5. Blue laser precision   In order to play back full- length feature movies, DVD-Video discs store digitally encoded video and audio information in the form of ‘pits’ that are impressed into a recording track that spirals out from the center of the disc to its edge. The different reflectivity of the pits enables the laser pick-up to read information from the disc. A fundamental law of physics states that the diameter of the laser spot is directly proportional to the wavelength of the laser light and inversely proportional to the numerical aperture of the objective lens (a figure that depends on the diameter of the lens, its radius of curvature and the material from which it is made). To reduce the size of the laser spot you can therefore use a shorter wavelength laser or increase the numerical aperture of the lens. Better still, you can do both, which is the approach adopted in the Blu-ray Disc specification. It results in the ultimate optical disc format, with the lowest achievable wavelength and the highest NA that is achievable under industrial conditions.
  6. 6.  Blu-ray Disc drives use a 405 nm blue laser and a lens with a numerical aperture of 0.85, instead of the 650 nm red laser and 0.60 numerical aperture lens used in current DVD drives.
  7. 7. Blu-ray Disc recording layer  The recording layer in a Blu-ray Disc sits on the surface of a 1.1-mm thick plastic substrate, protected by a 0.1mm thick cover layer. With the substrate material no longer in the optical pathway, birefringence problems are eliminated. In addition, the closer proximity of the recording layer to the drive’s objective lens reduces disc tilt sensitivity. This only leaves the problem of surface scratching and fingerprints, which can be prevented by applying a specifically developed, innovative hard-coat on top of the cover layer. This protective coat is hard enough to prevent accidental abrasions and also allows fingerprints to be removed by wiping the disc with a tissue. Both the cover layer and hard coat can be applied by low-cost manufacturing techniques such as spincoating.
  8. 8. Disc manufacturing     Despite the fact that Blu-ray Discs require the application of a cover layer and an optional hard coat, this should have little overall impact on disc manufacturing costs. DVD production.currently requires the injection molding of two 0.6-mm discs (one of which must meet stringent birefringence limits), the application of a recording layer to one of the discs, and a gluing operation to bond the two discs together. Blu-ray Discs only require the injection molding of a single 1.1- mm substrate with non-critical optical characteristics, which reduces injection molding costs. This cost saving offsets the additional cost of applying the cover layer and hard coat, while the techniques used for applying the recording layer remain the same. As a result, the overall cost of manufacturing a Blu-ray Disc will be no more expensive than producing a DVD, while some equipment such as injection molding machines can actually be used more efficiently. Because of the thinness of the cover layer, surface- flatness tolerances become far less stringent, while relative cover-thickness tolerances remain almost the same as for current DVD production.
  9. 9. Drive compatibility  Although no blue- laser disc will be readable using a red-laser, combined blue/red drives will be perfectly feasible. Servo- mechanisms that are capable of meeting Blu-ray Disc’s track positioning will be more than capable of meeting DVD requirements, while it should also be possible for both the blue and red laser to share a major part of the optical pathway. The relatively long development time for new drives means that drive manufacturers must stay well ahead of developments in optical storage so that they can get products to market quickly once a particular format gains market acceptance. With respect to Blu-ray Disc, several leading drive manufacturers have already demonstrated drives for consumer products such as video recorders that can read and write DVD and Blu-ray Discs.  According to the Blu-ray Disc v1.0 specification, 1x speed will require a 36Mbps data transfer rate, which means it will take about 1 hour and 40 minutes to record 27GB. The Blu-ray Disc Founders are currently working on the v2.0 specification, which will support 2x speed to cut the time it takes to copy content from one disc to another in half. In the future, the data transfer rate is expected to be raised to 8x or more.
  10. 10. CD, DVD, BD : A Comparison
  11. 11. Parameters BD BD DVD DVD Recording capacity 27GB 54GB 4.7GB 9.4GB Number of layers single-layer dual-layer single-layer dual-layer Laser wavelength 405nm 405nm 650nm 650nm Numerical aperture (NA) 0.85 0.85 0.60 0.60 Protection layer 0.1mm 0.1mm 0.6mm 0.6mm Data transfer rate 36Mbps 36Mbps 11.08Mbps 11.08Mbps Video compression MPEG-2 MPEG-2 MPEG-2 MPEG-2
  12. 12. HD - DVD   An alternative version has been developed by Toshiba and NEC and a provisional specification approved by the DVD Forum. The original name was AOD (Advanced Optical Disc). There are three versions in development.     HD DVD-ROM discs are pre-recorded and offer a capacity of 15 GB per layer per side. These can be used for distributing HD movies. HD DVD-RW discs are re-writable and can be used to record 20 GB per side for re-writable versions. HD DVD-R discs are write-once recordable discs with a capacity of 15 GB per side. Like Blu-ray discs they need a blue laser of 405 nm wavelength, but are physically similar to DVD discs, as they use a cover layer of 0.6 mm. Therefore HD DVD discs can be manufactured using existing DVD lines, and existing UV mastering equipment.
  13. 13. HD DVD vs BD  It is not yet clear which format will win. Blu-ray currently seems to have the most support, but HD DVD presents fewer manufacturing problems, particularly for pre-recorded versions. HD DVD can be mastered and replicated with current equipment, while Blu-ray requires new equipment and processes for both.
  14. 14. Uses and Necessity   As HDTV becomes more widespread, the consumer demand for recording HDTV programming will rise. Blu-ray was designed with this application in mind and enables direct recording of the MPEG-2 TS (Transport Stream) used by digital broadcasts, which makes it highly compatible with global standards for digital television. This means that HDTV broadcasts can be recorded directly to the disc without any extra processing or quality loss. To handle the increased amount of data required for HDTV, Blu-ray employs a 36Mbps data transfer rate, which is more than enough to record and playback HDTV while maintaining the original picture quality. In addition, by fully utilizing an optical disc's random accessing features, it's possible to playback video on a disc while simultaneously recording high-definition video. Blu-ray is expected to replace VCRs and current DVD technology within a few years. The format is also likely to become a standard for PC data storage and high-definition movies in the future.
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