One of the differences between the HD DVD and Blu-ray Disc formats is the discs' structure. Although both formats use the same laser wavelength (405nm), Sony’s format modifies the structure of the disc to achieve a higher value of numerical aperture, which allows Blu-ray Disc to store up to 25GB on the same area a HD DVD disc can store 15GB.

As a result, Blu-ray Disc is incompatible with HD DVD and DVD media because instead of having a 12mm thick disc made of a 0.6 mm disc with 0.6 mm protective coating on top (as in DVD media), Blu-ray Disc is made of a 1.1 mm disc covered by a 0.1mm protective layer.

Because of the different thicknesses of the protective layers, the data layers of both formats are at different depths from the surface and thus the components required to read or write them are different…until now.

The Nikkei Net Interactive reported over the weekend that Ricoh Technologies has developed an optical device that can read and write both next-generation optical disk formats.

The device in question is a diffraction plate that is placed between the laser and the lens, which allows changing the laser beam’s spot size on the fly. This will make possible to use the same components to read both Blu-ray Disc and HD DVD media. Hardware manufacturers would only need to make the diffraction plate change to the proper state depending on the media loaded in the disc drive.

"This diffraction device is the first one that is ready for four formats [CD, DVD, HD DVD and Blu-ray Disc], including BD and HD-DVD," a Ricoh spokesman told EETimes. "It will make it possible to build players and recorders ready for all formats, which will benefit consumers"

Ricoh will show the optical device later this week at the International Optoelectronics Exhibition '06 in Japan. We’ll have more on this new technology as it develops.

News-Source: http://news.teamxbox.com