Blu-ray : it is the newest optical disc format of today, being for many, the successor to DVD . Blu Ray was developed for the storage of a large amount of data, about 50 GB, and the execution of very high quality videos. While DVD uses a 650 nanometer laser, Blu Ray uses a 405 nanometer, making it possible to record more information on a disc of the same size.
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- 1 Technology
- 2 Competitors
- 3 Advantages of Blu-ray
- 4 Source
- 5 External links
A Blu-ray disc in its original form, inside a protective case. The minimum spot size at which a laser can be focused is limited by Diffraction , and depends on the wavelength of the light beam and the numerical aperture of the lens used to focus it. In the case of the blue-violet laser used in Blu-ray discs, the Wavelengthit is smaller compared to previous technologies, thus increasing the numerical aperture (0.85, compared to 0.6 for DVD). With this, and thanks to a dual lens system and a thinner protective cover, the laser beam can focus much more precisely on the surface of the disc. In other words, the readable information points on the disk are much smaller, and therefore the same space can hold much more information. Finally, in addition to improvements in optical technology, these discs feature an improved data encoding system that allows even more information to be packaged. The DVD had two problems that were tried to solve with Blu-Ray technology, so the structure is different. First of all, for reading on the DVD the laser must pass through the layer ofPolycarbonate0.6 mm in which the laser can be diffracted into two beams of light. If this diffraction is high, for example if it is scratched, it prevents the disc from being read. But said disk, having a layer of only 0.1 mm, avoids this problem, since it has less travel to the data layer; Furthermore, this layer is scratch resistant. Secondly, if the disc were tilted, in the case of DVD, for the same reason as the previous problem, the distortion of the laser beam would cause it to read in the wrong position, leading to errors. Thanks to the proximity of the lens and the fast convergence of the laser, the distortion is lower, being able to avoid possible reading errors. Another important feature of Blu-ray discs is their resistance to scratches and dirt. The thin separation between the reading layer and the surface of the disc made these discs more prone to scratches and dirt than a normal DVD. That is why it was first thought of marketing them in a kind of casing or Caddy. The idea was scrapped thanks to the elaboration byTDK of a protective substrate called Durabis, which not only compensates for brittleness, but also provides extra protection against scratches to said disc. There are also DVD discs with this protection, but it is not so necessary due to the greater thickness of the layer that separates the data from the surface of the disc, 0.6 mm.
Blu-Ray beat its competitor, HD DVD , in the format war, started to change the standard [[DVD | , as in its day occurred between VHS and Betamax, or the phonograph and the gramophone. Although others point out that the successor of the DVD will not be an optical disc, but the memory card . However, the HVD or Versatile Holographic Disk with 3.9 TB is being worked on. The capacity limit on SD / MMC format cards is already 128 GB, having the advantage of being rewritable for at least 5 years. In February 2008 , after the fall of much support for HD DVD, Toshibadecided to abandon the manufacture of players and research to improve its format. There is a third format, HD-VMD , which should also be named, since it is also focused on offering high definition. Its main disadvantage is that it does not have the support of large companies and is unknown by much of the public. That is why its main bet is to offer the same as the other technologies at a more affordable price, therefore part of the DVD technology (red laser). In the future, when blue laser technology is reliable and cheap, they plan to adapt to it.
Advantages of Blu-ray
In addition to the storage and high-definition advantages, one of the characteristics of blu-ray is the presence of a substrate in its composition, thus avoiding the appearance of defects from scratches. The main negative factor of this type of technology is the price of its components, quite high compared to DVD .