It’s called Blu-ray technology and it has become a standard feature of many personal media and entertainment devices, including the popular Playstation 3 video game console. However, of the millions of people who have heard of, used, or owned a Blu-Ray player, many may not know just what makes a Blu-Ray disc and its player different than its DVD relative.
At the heart of both the DVD and Blu-Ray is a laser sensor that scans over the “data layer” or coded side of the disc as it spins inside the player. From there, the laser transfers the information into a digital signal, which is then converted to the picture on your TV screen. However, the central distinction between a Blu-Ray player and a DVD player is that the Blu-Ray uses a blue optical laser instead of the red laser used by a DVD player. The blue laser has a smaller wavelength than its DVD competitor (405 nanometers, compared to the red laser's 650 nanometers), allowing it to be focused more precisely so that it can read data stored in smaller “packets” or groupings of coding. The smaller wavelength, combined with the smaller data packet size, allows for not only a greater amount of data to be stored, but also for faster reading of the data as the disc spins.
Because of the differences between a Blu-Ray player's blue laser and the red laser used by DVD players, Blu-Ray discs are constructed differently than DVDs. Whereas a DVD has its data layer sandwiched between two outer layers of polycarbonate plastic, a Blu-Ray disc has its data layer on top of a single layer of polycarbonate. A hard protective layer is then placed over the data layer to protect it from scratches and fingerprints. Placing the Blu-Ray’s data layer on top of a single polycarbonate layer allows the disc to be read more easily by the Blu-Ray player while preventing errors that can occur due to refraction or an uneven application of the disc layers, both of which are issues common to DVDs.
Going back to the essential commonality between DVDs and Blu-Ray discs (the use of a laser sensor to decipher the coding), it’s important to understand that there is a little more to it for the Blu-ray disc.
When a Blu-Ray disc is inserted into a player, the player's laser will scan the data packets near the center of the disc to get all of the basic information that it needs to play the disc. This data also contains information about how the disc is encrypted, allowing the player to decrypt the data, which was originally encrypted as a measure against piracy. Once the player has the necessary data and encryption details, it can then begin playing the disc, reading the data packets as the disc spins and converting them to digital video and audio information. This information is then sent to the television, monitor or other device connected to the Blu-Ray player, generally through the use of separate component cables or an HD cable connection. From there, the digital code is converted into the high-definition image you see on you TV screen.
Some information provided by eHow.com
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