Digital technology in its modern form is less than 50 years old, and therefore it is not surprising that all sorts of "updates" and format changes occur so often. Not everything has been invented yet. A great example of this is CDs, which today are experiencing a third birth and are given a third name: Blu-Ray.
Since Blu-ray is still a CD, the general concept remains the same. It is a piece of reflective plastic that has been laser-engraved with grooves of varying lengths. While reading a disc, the drive shines through it with a laser and monitors how the reflection from the mirror surface behaves. This is true for CDs, DVDs, and blue ray discs.
First and foremost, it is important to note the extensive improvements. Information is recorded and read using a much more precise laser: it is almost twice as thin as a DVD. In addition, the system for coding information during recording has been significantly improved. In total, the actual amount of data for one layer of disk space is 27 gigabytes, which is almost 5 times more than the old format we are used to. Moreover, only one layer is taken into account: back in 2009, a multi-layer disc with a volume of 500 gigabytes was developed, available for reading on any standard drive.
In addition to the obvious increase in volume, the coding system and the shortwave laser have significantly increased the speed of reading from the disc. Which, however, is natural - if the speed had not been increased, the drive simply would not have time, for example, to reproduce a high-resolution movie.
If we talk about fundamental innovations, then the “hard surface” of the disk can be considered as such. Thanks to Durabis Blu-Ray technology, the steel is several times more resistant to mechanical damage and, as a result, wear.
However, the main pride of the manufacturers is the security system developed for the new format. It consists of three elements: the BD + system, MMC technology and the ROM-Mark. The first allows you to dynamically (ie "on the fly") change the code sequence of the disk, protecting it from becoming a prototype of a pirated copy. The second, on the contrary, allows you to create copies, but in a special, protected licensed format. Finally, ROM-Mark technology leaves a special watermark on the disc, which cannot be faked and without which the drive will simply refuse to work.