The characteristics of each reproductive equipment indicate which region they can reproduce. Sometimes region codes are called regions. Region CodesĮach Blu-ray disc contains one or more region codes indicating where each distribution of the world is directed to. These protected DVD discs are also available but are not so necessary because of the larger layer thickness that separates the data from the disc surface by 0.6 mm. The idea was scrapped by the TDK, called Durabis, thanks to the development of a protective substrate that not only compensates for fragility but also provides extra protection against the scratches of the disc in question. So it was first thought to market them in some kind of case or Caddy. The fine gap between the reading layer and the disc surface made these discs more susceptible to scratches and dirt than normal DVDs. Thanks to the proximity of the lens and the rapid convergence of the laser, distortion is lower and possible reading errors can be avoided.Īnother important feature of Blu-ray discs is their scratch and dirt resistance. Secondly, if the disc is bent, in the case of the DVD, for the same reason as the previous problem, the distortion of the laser beam will cause errors to be read in the wrong position. However, having only a 0.1mm layer, this disc avoids this problem because it travels less to the data layer Also, this layer is scratch resistant. This prevents the disc from being read if the diffraction is high, for example, if it is scratched. First of all, to read on DVD, the laser must pass through a layer of 0.6mm polycarbonate, where the laser can break into two beams of light. Finally, in addition to advances in optical technology, these discs include an improved data encryption system that allows more information to be packed.ĭVD had two problems trying to solve with Blu-Ray technology, so the structure is different. In other words, the readable information points on the disk are much smaller, and therefore the same area can contain much more information. Thanks to this and the dual-lens system and a thinner protective cover, the laser beam can focus much more clearly on the disc surface. In the case of the blue-purple laser used in Blu-ray discs, the wavelength is shorter compared to previous technologies, therefore increasing the numerical aperture. The size of the minimum spot a laser can focus on is limited by diffraction and depends on the wavelength of the light beam and the numerical aperture of the lens used to focus it. Pioneer’s latest development has allowed it to create a 20-layer Blu-ray disc with a total capacity of 500GB, although it is not compatible with commercially available reader units, as Hitachi did. Hitachi also stated that it has developed a 200GB version. On October 3, 2007, Hitachi announced that, unlike the TDK and Panasonic version, it has developed a 100 GB BD-ROM prototype that is compatible with commercially available readers and only requires a firmware upgrade. On May 19, 2005, TDK announced the 100GB four-layer Blu-ray Disc prototype. Developed jointly by a group of technology companies called Blu-ray Disc Association (BDA), managed by Sony and Philips. The letter e, which is blue from the original word, has been removed because in some countries a common word for a trade name cannot be registered. This, together with other technological advances, allows the storage of significantly more information than a DVD on a disk of the same size and appearance.īlu-ray gets its name from the blue color of the laser beam. The Blu-ray disc uses a blue laser beam with a wavelength of 405 nanometers, unlike the red laser used in DVD players with a 650-nanometer wavelength. In the future, when blue laser technology is reliable and inexpensive, they plan to adapt to it. That is why its main commitment is to offer the same as other technologies at a more affordable price, so it is part of DVD technology (red laser). Its main disadvantage is that it does not have the support of large companies and is not known to most of the public. There is also a third format, HD-VMD, which should also be called because it focuses on delivering a high definition.
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