[Ceatec] TDK Develops 1TB-capacity Optical Disc

Oct 9, 2010
Tetsuo Nozawa, Nikkei Electronics
TDK's new optical disc (center). The piles of discs indicate the numbers of discs that are required to realize the capacity of 1 Tbyte.
TDK's new optical disc (center). The piles of discs indicate the numbers of discs that are required to realize the capacity of 1 Tbyte.
[Click to enlarge image]
[Click to enlarge image]

TDK Corp showcased an optical disc with a capacity of 1 Tbyte (1,024 Gbytes) at Ceatec Japan 2010, a trade show that runs from Oct 5 to 9, 2010, in Japan.

The company realized the large capacity by forming 16 recording layers, each of which has a capacity of 32 Gbytes on each side of the disc. The number of layers of an existing Blu-ray disc is four at most.

TDK succeeded in forming 16 layers by developing a disc material with a high light transmittance. Specifically, the light transmittance of one layer is 95.1%, and that of 16 layers is 72.6%.

"The material has already been used for part of a Blu-ray disc," the company said. "So, it does not have a problem of, for example, durability."

Because a beam with a numerical aperture of 0.85, which is also used for the Blu-ray Disc, is used for the new disc, many existing technologies for the Blu-ray Disc can be applied, TDK said.

The time it takes to read out one layer of the disc is the same as that of the Blu-ray Disc. The symbol error rate for reading out data ranges from 1 x 10-5 to 1 x 10-4, and TDK said that it is low enough for commercialization.

The only problem that has to be solved is the thickness of the disc.

"According to the specifications of the Blu-ray Disc, the thickness of a recording layer has to be 100μm or less," TDK said. "But the recording layer of the new disc is 260μm in thickness. And it causes the aberration of an optical lens."

The company expects that the new optical disc will be used as a home-use recording medium, a backup medium and a medium for a broadcasting service.

"Its commercialization depends on disc manufacturers," TDK said.