Toshiba makes a 36-Gbyte blue laser rewritable disk

Toshiba makes a 36-Gbyte blue laser rewritable disk
TOKYO — Toshiba Corp. will be presenting a paper at the Optical Data Storage meeting, held May 10-14 in Vancouver, Canada on its development of a dual layer 36-Gbyte rewritable disk for the Advanced Optical Disk (AOD) system.

The dual-layer disk is an effort to realize a 40-Gbyte capacity on each side using technologies similar to that of DVD.

The AOD system uses an objective lens with a numerical aperture of 0.65 and the same disk structure as DVD disks (two 0.6mm thick platters bonded together). The competitive Blue-ray Disk format uses a lens with a numerical aperture of 0.85 and a disk with a 0.1-mm cover layer, which makes the format incompatible with the DVD format.

The AOD disk is a phase-change disk whose recording layers are made of a germanium-tellurium-rich germanium-antimony-tellurium-bismuth alloy. The capacity target is 40 GBytes.

Sony Corp. introduced the first Blu-ray Disk recorder just last month that used a single-layered 23-Gbyte disk. For its part, Matsushita demonstrated a Blu-Ray dual-layer disk with 50-Gbyte capacity in 2001.