DVD RW

DVD-RW, which stands for Digital Versatile Disc ñ Rewritable, is a data storage medium. With a capacity of up to 4.7 GB, this disc can be used to store just about any kind of data including movies and music files. Even though DVDs are of the same size as conventional CDs, they have almost 6 times the capacity. The RW clause in DVD technology implies that the data stored on the DVD can be erased and rewritten with other data as many as 1000 times. Considering the high storage capacity of the disc, both video and audio files that are stored on them do not require any compression; a fact that converts into superior video and audio clarity. Since DVD-RWs can be used for multiple recordings, these discs make more economical sense as compared to DVD-Rs that can be written only once.

In DVD-RWs, the disc is uniformly covered with a recording layer composed of a metal alloy, usually GeSbTe. This alloy incorporates a phase change technology, which involves a thermodynamic system undergoing an instant change in some of its physical properties. In the case of the DVD based alloys, the reflectivity crystalline and amorphous phases vary. Since the states can be switched when the intensity of the writing laser varies, the existing data can be erased and rewritten. DVD-RWs are usually read by a red laser beam that gets focused on the rotating surface of the DVD. A sensor reads whether the laser beam gets reflected or not and this information is converted into binary digits.

The writing of DVD-RWs are controlled by international industry specifications. This ensures uniformity in DVD formats as far as optical signal characteristics, physical arrangement, mechanical properties, and writing techniques are concerned.