Dual Layer DVD

How It Works

As the name suggests, the extra recording capacity is made possible through the addition of a second recording layer inside the disc. To make it possible for a single laser to access both recording layers, one behind the other, the top layer has been made semi-transparent. That allows enough reflectivity for data storage and playback while also allowing light to pass through to the second layer.

An alternative to dual-layer technology is double-sided discs. These offer double the storage space at 9.4GB but require the user to take out and flip over the disc to gain access to the second side. Such discs are already on the market.