by Anton Shilov
10/15/2009 | 08:26 AM
TDK has developed and demonstrated its Blu-ray disc (BD) media with 320GB capacity. The write once disc features ten layers and each layer sports higher than standard capacity, which means that the media is incompatible with existing Blu-ray players.
TDK’s 320GB disc sports ten layers and each layer has storage capacity of 32GB, up 7GB from standard 25GB, reports Tech-On web-site. According to the media report, it is possible to write and read data on and from the disc by using a blue-violet semiconductor laser with an oscillation wavelength of 405nm and an objective lens with a numerical aperture (NA) of 0.85, which are currently used for the Blu-ray disc. Still, according to Blu-ray disc association (BDA), BDs with higher than 50GB capacities are incompatible with existing players.
The capacity breakthrough is achieved by using different materials for the layers: the L0 layer consists of Si-Cu alloy, whereas the L1 to L9 layers consist of either bismuth peroxide or germanium dioxide.
TDK exhibited its 320GB media at Ceatec Japan trade-show earlier this month.
The 320GB media from TDK boasts impressive capacity, but it is not the highest-capacity Blu-ray disc ever demonstrated. Pioneer Corp. said in mid-2008 that it had succeeded in developing a 16-layer read-only optical disc with a capacity of 400GB for the first time in the world. Later in 2008 Pioneer also said that technology-wise it could develop a 500GB BD.
Earlier this month the BDA said officially that existing Blu-ray disc players would not be compatible with 100GB or 200GB BD media. Nevertheless, BDA indicated that 50GB should be enough for movies for many years to come.
“I think there will be applications for larger capacity recordable discs, but it would be difficult for [discs larger than 50GB] to achieve compatibility with the installed base of players. This is because player manufacturers design players to meet published specifications that define maximum media capacity, which in the case of Blu-ray Disc, is 50GB on two-layer media,” said Andy Parsons, the chairman BDA’s promotion committee in the U.S., in an interview with Home Media Magazine.