Not content with the single- and dual-layer Blu-ray discs currently flooding the market, Pioneer has developed a disc that holds a whopping 16 layers. Purportedly the first of its kind, Pioneer's 16-layer, read-only disc uses the same 25GB-per-layer density as standard Blu-ray for a total capacity of 400GB per disc.
As one would expect, preventing interference to make all 16 layers readable involved some challenges. Pioneer says it managed to overcome those obstacles using its experience in DVD technology and other techniques:
For multilayer optical discs, it has been difficult to obtain clear signals from each recording layer in a stable manner due to crosstalk from adjacent layers and transmission loss. Utilizing the optical disc production technology that it has developed in the DVD field, Pioneer solved these problems by, among other things, using a disc structure that can reduce crosstalk from adjacent layers, resulting in a 16-layer optical disc that can playback high-quality signals from every layer.
As for the read-out system, Pioneer achieved stability in the playback of recorded signals by employing a wide-range spherical aberration compensator and light-receiving element that can read out weak signals at a high signal-to-noise ratio in the optical pick-up mechanism.
Pioneer mentions that its disc requires the same objective lens specifications as existing Blu-ray discs, making backward-compatibility "possible." Also, the company plans to apply its multi-layer technology to recordable discs.
You can expect Pioneer to reveal more about the prototype at the International Symposium on Optical Memory and Optical Data Storage in Hawaii on July 13.