DVD-R

DVD-R stands for Digital Versatile Disc - Recordable. It is a type of write once, read many DVD format that allows the user to recorded a single time on a DVD disc. The specifications are contained in Book D.  Similar to the CD, the DVD can contain any type of information, such as video, text, audio, and computer data, for example. DVD-Rs are read at the same speeds as commercially made DVDs. The recording process is very similar to that of CD-Rs. A layer of organic dye  that is permanently changed by exposure to a finely focused laser beam is used. The dye layer is found on top of the polycarbonate plastic substrate (the base layer of all CDs and DVDs). It has a pre-grooved spiral track to guide the reading and writing lasers. To increase the storage capacity of DVDs, both the wavelength and sperture size of the laser are reduced so that smaller pits are formed. These smaller pits give greater compression ability. Once the data has been written, the dye layer is coated with a thin, reflective metal coat that will enable the laser to read data from the differences the way the pits and lands reflect light.