At this year's Consumer Electronics Show, Hitach-Maxell demonstrated a 4 layer 100GB Blu-ray disc. Since then, the company has taken this
technology one step further, doubling the number of layers and boosting the capacity to 200GB. Here's part of their press release,
translated from Japanese:
The hitachi, ltd. Research Center (chief: Yasushi Hukunaga/below, Hitachi), this each time, basic
technology of the optical system which expands the regenerative signal output of the optical disk in 10 times was developed. As for this
technology, it is something which makes the optical detection method which expands the regenerative signal making use of the interference
of two lights the optical disk apply. With this technology, reflected light of the optical disk being weak, accurate reading of the
regenerative signal becomes possible, you say that reflected light becomes weak by the fact that the number of record layers increases
fundamental topic of the multilayer optical disk is solved, the blue ray disk whose record playback of the single sided 100~200 gigabyte
is possible at 4~8 layer (Blu-ray Disc) actualization of the device is expected.
While details are sketchy due to the
translation, Hitachi appears to be splitting the laser in half to create a reference beam. This second beam helps cut through the
interference caused by the layers being so close to each other. According to other, unconfirmed sources, Hitachi plans to bring this
200GB disc to market by 2009. If you'd like to read more, their entire press release can be found here.
