By BBC News Online internet reporter Mark Ward Digital disks are set for a big boost in capacity. By the end of the year, US firm Constellation 3D claims that it will be selling a new generation disk it hopes will replace existing DVDs Initially the new disks will have 10 times the capacity of a DVD, and by the middle of next year, the company says it will be making disks with 20 times more storage room. Constellation claims that existing DVD drives will be able to read its disks after only a slight modification. The company says it can squeeze a lot more data on to a disk because it has found a way to record information on multiple layers within the disk.
Every layer holds the equivalent of an existing DVD - around five gigabytes of data.
Currently, Constellation has made disks with 10 layers but expects that as the technology improves it will be able to make 100-layer disks. A laser reads the sequence of different length pits and lands, and this is converted into a stream of digital information. DVDs use more powerful red lasers than those in a CD player. This means that the pits and spaces can be smaller and more information can be crammed on to the disk. By contrast, the new Constellation disks overlay the pits and lands with a fluorescent material which emits light when struck by the laser.