Blu-ray Disc recordable
The BD -RE is rewritable format of Blu- ray Disc and is therefore contrary to the write-once BD -R. The abbreviation RE stands for Recordable Erasable. Current single-layer blanks are available in capacities of 23.3 and 25 gigabytes. The double variant offers 46.6 and 50 GB.
The rewriting is possible through the use of phase - change technology. Unlike a DVD ± RW can be rewritten at least 1,000 times and provides greater data security is not enough for both properties but closer to the DVD-RAM. Some manufacturers already apply BD -RE that should be up to 10,000 times rewritable. The lifetime of the data is indicated by 30 to 50 years.
In the future, it should also give media with a capacity of 27 gigabytes per layer.
In addition to discs with diameter of 12 cm even they exist with 8 cm. The capacity of 8cm discs is (single ) at 7.8 GB and 15.6 GB (double layer ).
A single-sided recordable BD -RE is composed of seven layers. Starting from the label side of the laser is in the direction of the first layer of the substrate ( carrier layer ) which is made of polycarbonate. It has been worked groove surface, propagates from the center to the edge of a spiral. On the substrate, a silver alloy layer is applied, which is responsible for the reflection of the laser. There is a dielectric layer of zinc sulfide and silicon dioxide on this layer. It joins the recordable layer (even phase-change layer called ). It can be composed of a germanium -tellurium -antimony, or indium - silver - antimony - tellurium alloy. It is followed by a further dielectric layer and after a polycarbonate or silicone top coat. In most cases, a protective layer (hard coat layer) is also applied from plastic resin, which negates the need for cartridges.
In summary, the structure:
In a double-layered BD-RE follow the outer dielectric layer, a spacer layer ( dissociation layer) and the second rewritable layer, surrounded by two dielectric layers. The structure looks as follows:
The preferred file system for BD -RE is UDF version 2.5. In principle, any file system can be used, but with other systems as UDF 2.5 rarely be achieved provided the 1000 rewrite operations.