Unveiled: Super-multilayer BD-R disc with 320GB recording capacity
TDK has exhibited a 10-layer recordable disc that can store up to 320GB. Maximum recording capacity for currently available BD-R discs is 50GB (dual-layer).
Transmittance raised to the nth degree
Staff explained that, to create a disc with 10 recordable layers, the transmittance of each layer had been "raised to the nth degree." The transmittance of the uppermost layer exceeds 90% whereas it is only 50% for a conventional dual-layer disc. Even at the lowest layer (L0) signal characteristics are good and the error rate is within the range that can be managed using conventional error-correction methods.
The Blu-ray standard allows for up to 8 layers, which should peg maximum capacity at 200GB. This new disc from TDK thus exceeds the layer limit set by the current standard. "As a member of the Blu-ray association, TDK will propose that the standard be expanded," explained a staff member. "Standard hardware with modifications" is reportedly being used for recording these discs, suggesting that development of a player/recorder is not going to be too difficult.
With 10 layers storing a total of 320GB per disc, the capacity of each layer is 32GB, a figure that exceeds the 27GB maximum set for the Blu-ray disc format. "The modulation method has not been changed," according to TDK staff. "Layer capacity has been increased by employing a smaller track pitch".