If 50GB Blu-ray disks aren't quite cutting your particular optical storage mustard, then you might want to check out TDK's whopping great 320GB prototype.

Although it's technically not a true Blu-ray disk, the new write-once medium uses the same read/write technologies as BD, so that's good enough for us.

Layers of data

The trick to TDK's breakthrough lies in getting that same blue-violet semiconductor laser to penetrate all the way through each of ten layers to properly read from and write to even the innermost layer.

With 32GB per slice, that adds up to 320GB overall – a considerable improvement on a 2006 six-layer TDK disk that topped out at 200GB.

Although there are no commercial plans for the disk yet, it will be on show next week at the Ceatec technology event in Japan.