While TDK's 100GB and 200GB Blu-ray Discs never made it past the prototype stage, this hasn't stopped the company from pushing the technology to new limits. According to the Japanese website, Tech-On!, TDK has now developed a 320GB optical disc. These discs contain 10 layers, with each layer capable of storing 32GB. TDK plans to exhibit this new technology at CEATEC 2009.
The new optical disc has a larger capacity than the Blu-ray disc, which has a capacity of 25 Gbytes per layer. And 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...
...The structure of the new disc is as follows. A cover layer and a hard coat layer, which protects the surface from scratches and dirt, are formed on recording layers (the innermost L0 layer to the outermost L9 layer). A Si-Cu alloy layer, which is inorganic, is used for the L0 layer.
