HD DVD recorders are devices used for writing data onto a disc, namely to record TV shows and movies with a higher quality sound and image and a greater storing capacity than the standard DVD recorders. The latter were considered the intermediate between the classical, old-fashioned VHS tape and a CD burner. One can differentiate two formats that work with this device, namely DVD-R and DVD+R, but, since the latest models of DVD recorders can support both formats, it doesn’t make much of a difference.
HD DVD recorders have the capacity of recording 3 times as much data per layer as their predecessor (which means a maximum of 4.7 GB or 9.4 GB, for the single and dual layer DVD respectively). However, this storing space is not enough for a two-hour movie in HD format, which entails you need two discs for such a movie.
The article will next deal with the way in which HD DVD recorders work. Such a device uses to lasers to perform a reading action and a writing one. They feature a small data layer made out of foil coated with dye that is covered on both sides with protective plastic plates. While this data layer (DVD that is) spins round, the laser shines through the transparent dye and makes it translucent. Each translucent portion represents a bit of information and the mechanism of imprinting such spots defines the burning or writing process. In order to read this information, the DVD recorder sends a weaker laser at the data plate. If the laser meets unwritten dye portions, it will bounce back.
HD DVD recorders employ several types of discs. Depending on their structure, the discs can be single- or dual-layered. The former category is defined by a capacity of 15 GB for HD DVD-ROM, HD DVD-R and HD DVD-RW, and one of 20 GB for HD DVD-RAM, whereas the latter is associated with a capacity of 30 GB. The data layer is protected from damage due to its positioning below the surface with 0.6 mm. They are backward compatible with DVD and CD and have a numerical aperture of the optical pick-up head of 0.65, compared with 0.6 for the standard DVD recorders.
Unfortunately for this type of device, the supremacy in the field of high definition optical disc format was adjudged in 2008 by Blu-Ray, a more efficient format developed by Blu- Ray Disc Association. In order to write data, the latter format used a blue laser which has a shorter wavelength than the red lights employed by HD DVD recorders, which allowed a greater storage capacity on a Blue-Ray Disc.