Back in July word came out that Pioneer had developed a 400GB optical disc based on Blu-ray. This ability to grow to high densities is one of the primary reasons Blu-ray was superior to HD DVD, IMHO. And the best news was that Pioneer claimed the new discs could be read by existing Blu-ray drives. But nothing had really been heard since the first articles.

Now DIGITIMES has spotted the disc being exhibited at the IT Month fair currently taking place in Taipei, Taiwan. As before it is a 16-layer read-only disc, 25GB per layer just like Blu-ray. And they’re working on a 500GB, 20-layer version, with a 1TB target by 2013. The current version is targeted for 2008-2010, with rewritable discs in 2010-2012.

Spotted via Gizmodo.

It is no secret that I’ve been a Blu-ray supporter since before it was called Blu-ray, before there was any format war. And one of the reasons for that is that it is has always been the technology with a lot of growth potential. While HD DVD was pushing DVD technology to its limits, Blu-ray laid the foundations for future expansion.

We’ve already seen prototypes of 100GB and 200GB evolutions of Blu-ray. Now Pioneer has pushed Blu-ray technology to 400GB! Both PC World and TechRadar UK reported on the development. Best of all, it is reportedly backward compatible with today’s Blu-ray hardware. In theory that means existing drives could handle the higher capacity media with a firmware update.

Pioneer has achieved this capacity by stacking sixteen 25GB layers, compared to the two 25GB layers on a standard Blu-ray disc. They’ve done this by solving the interference issue which results from stacking an increasing number of data layers on top of each other. But they’ve managed to do so using the same optical specifications of the objective lens, maintaining Blu-ray compatibility.

Expanded capacity like this would likely first be used in data applications, for backup, etc. While some unusually long films might be able to use more than 50GB for HD home video, 50GB is enough for most videos up to 1080p. But there are already newer video standards appearing, such as 3D video or 4k video, which is 4096×1716. That’s the resolution used for digital cinema projection in movie theaters, and it is nearly 3.5x the resolution of ‘Full HD’ 1080p home video. When you go to higher resolutions and/or add data to support 3D displays, then you need higher capacity media.

Backwards compatibility could be useful as such discs could use the ‘top’ two layers just like a standard Blu-ray disc that would work in any existing player. While the remaining layers could be used for newer standards like 4k or 3D, and work in newer players that support those technologies.