The Blu-ray Disc belongs to a new generation of optical discs capable of staging high density data. Blu-Ray technology is based on a blue-violet coloured laser. The blue laser operates at a wave length of 405 nm, while older technology such as DVDs and CDs are based on red and infrared lasers that works at 650 and 780 nm. Since the wave length is shorter with a blue laser, the new Blu-ray technology makes is possible to store much more information
The advantage with the Blu-ray technology is that the laser beam can be focused much more tightly at the surface of the disc. Tight focus means that a smaller spot will be produced on the surface on the disc, and when the spots become smaller there will naturally be room for more information on each disc. The minimum spot size of any laser depends on a naturally accruing phenomenon called diffraction. The narrow beam of light sent out from a laser will always diverge into a wider beam eventually, due to the natural diffraction of waves. Diffraction will also occur the waves meet an obstruction. By reducing the wavelength of a laser, we can affect the diffraction.
In Blu-ray technology, the diffractions is also affected by the fact that the lens used to focus the light has a higher numerical aperture than the lenses found in ordinary DVDs – 0.85 instead of 0.6. Blu-ray technology based appliances are also equipped with a dual-lens system of supreme quality, and the cover layer has been made thinner in order to prevent unwanted optical effects. All this makes it possible for a Blu-ray laser to focus on much smaller spots. The optical improvements are accompanied with a new method for encoding data which makes it possible to store even more data on the Blu-ray disc.
The standard for Blu-ray technology has been developed as a joint venture between several major manufacturers of PCs and consumer electronics, including Sony and Philips. The group is called the Blu-ray Disc Association (BDA). The first Blu-ray recorder was launched in Japan in 2003, by Sony. Today, Samsung, JVC, Matsushita (Panasonic) and LG Electronics are all examples of companies using Blu-ray technology in their products. Hewlett Packard has announced that they will release desktop PCs equipped with Blu-ray technology in late 2005.
The main competitor for the Blu-ray technology is the HD DVD format which is also capable of storing more information than a normal DVD. The Blu-ray technology does however allow for more information per layer than the HD DVD format – 25 GB compared to 15 GB. The Blu-ray technology will on the other hand most likely be more expensive to support, at least initially, which can make the HD DVD a tempting alternative. In a Blu-ray disc, the data is stored extremely close to the surface. This made the first Blu-ray discs extremely vulnerable to scratching and many users preferred the tougher HD DVD discs. Since 2004, all Blu-ray discs are coated with a clear polymer called “Durabis” which makes them much more durable. According to the developers of Durabis, the TDK Corporation, a coated Blu-ray disc will work even after being attacked with a screwdriver.
BLU-RAY VS DVD
Video technology has increased significantly over the past years, and is continuing to grow at an incredible rate. Digital Video Disc’s aka DVD’s are the most likely the last big jump in consumer video technology that everyone is familiar with. To keep up with the ever advancing world of electronics a new format of video storage will be released soon called Blu-ray.
Blu-Ray is a next generation optical disc that will blow the socks off of what we all know today: DVD. Conventional DVD’s use a red laser that have long wave lengths, which limits the storage capacity on a disc. Blu-Ray uses a blue laser which has much shorter wave lengths. Because the wave lengths on the Blu-Ray are much smaller it can focus on a spot with much greater precision, allowing for data to be packed much more tightly than the red laser DVD’s.
Blu-Ray discs can hold up to 50GB’s of information which 10 times that of a 4.5GB DVD. 10 times the storage will greatly increase the amount of information that we can save on any one disc and will change the way we save information. Dual Layer Blu-Ray discs will be able to hold up to 4 hours of High-Definition Video. High Definition video is going to hit big here, Blu-Ray is an example of a technology that is going to make it happen. 50GB is probably comparable to size of many of our hard-drives, and to picture having all of that information on a small disc that we can slide into a pocket and take wherever we want is a bit scary.
Expect to see Blu-Ray replacing DVD and VCR over the next few years, following along with the transition of video to High Definition Video. Video isn’t the only thing that will benefit from Blu-Ray technology; I would expect that it will also become the standard for PC and other types of storage.
The current aim of blu-ray and HD-DVD is to get as much public support quickly as ultimately it is the consumer who will decide which format comes out on top. With the unification talks failing it is up to you to make the decision of which format to adopt. To help you with this tough decision is the lowdown on how each format matches below.
The blu-ray format’s head companies are Sony and Philips with Toshiba and Hitachi heading up the HD-DVD format. This situation isn’t the first time where these two sides have gone at each other with opposing formats. The DVD format was born from the co-operation of the Multimedia Compact Disc from Sony/Philips (MMCD) and the Super Density Disc (SD) from Toshiba. Though it ended well for the consumer with the DVD format being widely adopted and becoming the new standard, it was Toshiba’s camp who came out on top in regards to royalties.
This led to the work on new formats by both sides with Sony aiming to regain some of its lost market. The two projects though had been in production but not really going anywhere at the time. Sony’s Professional Disc for Data (PDD) became the blu-ray format while Toshiba’s Advanced Optical Disc becoming HD-DVD. This leads us back to the original situation where there are two competing formats with a unification looking a lot less likely.
Both blu-ray and HD-DVD use a wavelength of 405nm however the smaller track pitch on blu-ray (see Blu-ray Disc) allows more information to be squeezed on and so gives the larger capacity. However it is the differing track pitch that makes these two formats incompatible. The surface layer of the two is different also as HD-DVD uses a 0.6mm layer similar to DVD whereas blu-ray uses a 0.1mm clear plastic layer.
This difference is the main reason why costs are higher with blu-ray. Costly production methods are needed to be able to make the discs and a hard coating must be applied to make the discs suitably resilient to dust and fingerprints.
Blu-ray currently offers discs in 25gb for single layer and 50gb for dual layer. However TDK has started work on a 200gb disc which is 6x33gb layers.
HD-DVD comes in 15gb for the single layer and 30gb for the dual layer. Best tests so far have achieved 45gb but 60gb is the theoretical limit. This shows that the maximum for HD-DVD is only 10gb more than what blu-ray can already offer.
Both formats use the same codecs to play video as they are both able to play standard and high-definition. This means that MPEG-2, Microsoft Video Codec 1 (aka VC1, WMV HD, etc.) and H.264 / MPEG-4 AVC are all supported on both formats.
Both blu-ray and HD-DVD have to make use of HDCP encrypted output and the Advanced Access Content System (AACS). Both HDCP and AACS are mandatory for any discs with HD video.
Blu-ray also incorporates ROM-Mark watermarking technology and BD dynamic crypto which generates special keys for batches of discs.
HD-DVD uses a similar system in the Volume Identifying technology.
Both formats are heavily supported in both the Consumer Electronics (CE) and Information Technology (IT) industries. However blu-ray has a better portion of the big name movie and game studios supporting it which is essential for there to be a ready amount of content at launch. See below for the list of Supporting studios:
20th Century Fox
Buena Vista Home Entertainment
Sony Pictures Entertainment
The Walt Disney Company
Vivendi Universal Games
Buena Vista Home Entertainment
New Line Cinema
The Walt Disney Company
Josh Biggs is the founder of Blu-ray-review.co.uk which gives the visitor a resource for all the latest blu-ray news and product reviews with community discussion.
UNDERSTANDING COMPUTER OPERATING SYSTEMS