The operation of a compact disc takes much more physical back than one could imagine at first. We must know that the amount of layers, thickness, durability, strength and storage capacity of a disk depends on the technology used.
The information of the disc is in the inner part of the polycarbonate layer and to read this information we need the laser of the reader. The Blu-ray disc makes use of a blue laser beam with a wavelength of 405 nanometers, unlike the red laser used in DVD readers, which has a wavelength of 650 nanometers. This, together with other technological advances, allows to store substantially more information than the DVD on a disc of the same dimensions and external appearance. Blu-ray gets its name from the blue color of the laser beam (blue ray means 'blue ray').
The reader also has a sensor (photodiode) that receives the laser light reflected in the aluminum layer. Before, this laser light has to go through the polycarbonate layer and undergoes different changes depending on how each point of this layer is. And is that the polycarbonate layer is not completely smooth but has small slits (pits in English) that cause alterations in the laser light.
What this laser does is to "illuminate" each point of the disc and to check if there is a slit or a plain. The laser knows in which zone we are since when there are no changes, that is to say there is a sequence of plain or slit, the laser reflects and reaches the sensor well. While when a variation occurs, that is to say we pass from slit to plain or from plain to slit, the reflection angle changes and the laser light does not reach the sensor. So we already have the binary representation that the computer understands: the zone of non-variation is assigned the value 0 and when a change is made it is assigned the value 1. The sequence of 0 and 1 is what allows you to know the computer what information is stored on the disk to be able to play it on the screen.
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 0.6 mm polycarbonate layer in which the laser can be diffracted into two light beams. If this diffraction is high, for example if it is scratched, it prevents the reading of the disk. But this disk, having a layer of only 0.1 mm avoids this problem, since it has less travel to the data layer; In addition, this layer is resistant to scratches. Secondly, if the disc were inclined, in the case of the DVD, for the same reason as the previous problem, the distortion of the laser beam would make it read in the wrong position, giving rise to errors. Thanks to the proximity of the lens and the fast convergence of the laser, the distortion is lower,
Another important feature of Blu-ray discs is their resistance to scratches and dirt. The thin separation between the reading layer and the disc surface 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 housing. The idea was discarded thanks to the development by TDK of a protective substrate called Durabis, which not only compensates for the fragility, but gives extra protection against scratches to the disc. There are also DVD discs with this protection, but it is not as necessary due to the greater thickness of the layer that separates the data from the surface of the disc, 0.6 mm.
The discs are composed of different layers:
POLISHING OF DISCS
In Arcadia we have a modern team to leave your records as new. We have the technology to repair music discs, DVDs, video games, rewritable discs, Blu-ray and other disc formats. Our equipment automatically adjusts to the type of disc that will be polished, allowing you to adjust the polishing time. The number of times the disc has to be polished depends on the depth of the scratches.
CONDITIONS FOR THE DISCS POLISHING SERVICE:
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