Just a little than a month after Pioneer Corp. unveiled its technology that could power Blu-ray disc (BD) media with 400GB capacity, the company said that its technologies also allow creating 500GB Blu-ray disc. The company this time did not remain tight-lipped over the timeframe when half a terabyte optical discs are set to become available and provided a guidance.

Apparently, Pioneer's multi-layer disc technology allows to create optical disc with 20 layers, which provides 500GB in total. Pioneer said that the International Symposium on Optical Memory (ISOM) and Optical Data Storage, held during July in Hawaii, where Pioneer Corporation presented its research, defining had previously outlined the industry objective of creating a 20-layer disc to be available between 2010-2012.

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. Since the optical specifications of the objective lens, such as numerical aperture (the higher numerical aperture of the objective lens, the smaller diameter of the beam spot focused on a disc surface), are the same as those for the existing BD discs, it is possible to maintain compatibility between the new 16-layer optical disc and the BD discs.

The 16-and 20-layer optical disc technology, capable of storing much more data than the conventional discs on one disc, will greatly reduce the number of discs to be used and therefore contribute to the conservation of resources.