(_What is the diff in Blue-Ray Disc's and DVD's?_)?

Answer:

About 9 hours of high-definition (HD) video can be stored on a 50GB disc.

About 23 hours of standard-definition (SD) video can be stored on a 50GB disc.

The Blu-ray Disc system uses a blue-violet laser operating at a wavelength of 405 nm, similar to the one used for HD DVD, to read and write data. Conventional DVDs and CDs use red and infrared lasers at 650 nm and 780 nm respectively.

Hard-coating technology

TDK 100-gigabyte four-layer Blu-ray Disc.

Enlarge

TDK 100-gigabyte four-layer Blu-ray Disc.

Because the Blu-ray Disc standard places the data recording layer so close to the surface of the disc, early discs were susceptible to contamination and scratches and had to be enclosed in plastic caddies for protection. The consortium worried that such an inconvenience would hurt Blu-ray Disc%26#39;s market adoption in the face of the rival HD DVD standard, as HD DVDs place the data layer farther away from the surface, rather like DVDs. Blu-ray Discs now use a purpose-developed layer of protective material over the reflective data backing (i.e. on the label side).

Both Sony and Panasonic replication methods include proprietary hard-coat technologies. Sony%26#39;s rewritable media are sprayed with a scratch-resistant and antistatic coating.

TDK also announced a way to remedy the problem in January 2004 with the introduction of a clear polymer coating that gives Blu-ray Discs substantial scratch resistance. The coating was developed by TDK Corporation and is called "Durabis". It allows BDs to be cleaned safely with only a tissue. The coating is said to successfully resist "wire wool scrubbing" according to Samsung Optical technical manager Chas Kalsi. It is not clear, however, whether discs will use the Durabis coating or if the use of the coating will prove too expensive.

Verbatim announced in July 2006 that their Blu-ray Disc recordable and rewritable discs would incorporate their hard-coat ScratchGuard technology which protects against scratches, abrasion, fingerprints, and traces of grease.