Blu-ray technology is a thorough new optical storage medium that is jointly developed by ten companies. High-definition TV recording may be the initial power development of Blu-ray, but it is not the only application for the huge storage capacity and high data transfer rate of blue light.
The accuracy of the blue laser: In order to play the entire movie, the DVD disc is screwed from the center to the disc track from the center in the form of a groove. Different reflectances of the grooves make the laser read information from the disc. To ensure that there is enough coded data to store high-definition and television, the disc capacity is at least five times the DVD. In order to ensure that such a large amount of data can engrave on the 12 cm optical disc of a cheap single side, the size of the groove must be tapped, and the laser read the head can be focused on the top. The basic physical law defines the diameter of the laser concentrate and the wavelength of light, and the digital aperture is inversely proportional. So you can narrow the laser point with a shorter wavelength or a larger digital aperture. These two efforts have been adopted by the Blu-ray specification. This produces the final disc format, the minimum wavelength and maximum NA value allowed under industrial production conditions. The Blu-ray driver uses a blue laser and 0.8 diamond of the wavelength of 405 nm to replace the 650 nm wavelength and 0.6 aperture for DVD. This allows the Blu-ray driver to read a bore of 0.15 micrometers (more than 60%) than the DVD). At the same time, the rail gap is reduced from 0.74 to 0.32 microns, which allows a single-sided Blu-ray disc to store 25GB of data, enough to play a high-definition TV for 2 to 3 hours. Blu-rays are not just a pure technical solution, and it takes into account the business recognition. Blu-ray diodes are more easily accepted, optical focusing and servo systems and current high flow water production lines are more compatible. Moreover, the Blu-ray optical disc can be manufactured with a device that presses CD and DVD. Unlike CD and DVD in order to consider more compatibility, you must write write, rewritten, and read-only, and Blu-ray will be used as a target. The use of phase transform technology Blu-ray-random access includes simultaneous reading and writing, and is compatible with PC digital products, data, and image height. Blu-ray record layer: An important feature of a distinguished blue and DVD is a record layer in the disc. The DVD is sandwich: sandwiched by two pieces of 0.6 mm polycarbonate, in order to prevent scratches, fingerprints and dust on the reading data of the laser header. However, this also has a disadvantage. To make them with a stamping process, the photosensitive underlying of the optical discs suffer from birefringence caused by pressure, which means that the laser bundle of the incident is divided into two bouquels. If this reflection is too much, the drive cannot be stably read data. Therefore, the stamping process has always been the most controversial part of CD and DVD. Another controversial machine component is a plate plane because if the disc is tilted, the laser beam is distorted, especially DVD. This distortion increases as the thickness of the protective layer and the increase of the digital aperture. In order to overcome these disadvantages, the blue-ray record layer is used in a 1.1 mm sensor underlayer, with a 0.1 mm protective layer. Because the photosensitive bottom layer is no longer in the visible light range, the birefringence problem is solved. Moreover, the data recording layer and the drive objective are closer to reducing the sensitivity to the tilt. In order to prevent scratches, fingerprints, we use innovative hard shell protective layers. This protective layer is sufficient to prevent accidental wear and can remove the above fingerprints with a thin yarn paper. Both the cover layer and the hard shell can be fabricated in a production process similar to a rotating feeding. Made of discs: Although blue is required to cover the layers and alternative hard shells, this does not bring huge impact on the cost of disc production. The manufacturing of the DVD requires a 0.6 mm protective layer of injection on both sides, one-sided recording layer, as well as adhesives stick these. Blu-rays require only 1.1 mm injection molding, and has no disputeous optical properties, which reduces the cost of injection molding. This part of the cost makes up for the cost of covering and hard shells. Therefore, the overall cost of manufacturing a blue-ray disc does not compete than DVD, but some equipment such as injection molding is more efficient. Because the protective layer is thin, the error of the table plane is not so important, and the overlay error is still the same as DVD.
