DVDs promise a capacity 14 times conventional CDs

17 Jun 2002

Digital versatile discs (DVDs) will appear in consumer products in early 1997. The same size as conventional compact discs (CDs), DVDs will hold about 14 times more data because of a combination of innovations. Both types of discs encode digital data as pits on thin plastic platters, but for DVDs the pits are smaller (.4 microns versus .83 microns for CDs), the tracks of pits are closer together (.7 versus 1.6 microns), and the laser light used to read data has a wavelength of 635-650 nm rather than the 780 nm used for CDs allowing data to be crowded in more densely.

With a capacity of 4.7 Gbytes, the DVD will be able to provide a variety of multimedia products, even movies, at least in compressed form. And all of this is without resorting to blue-light lasers under development, whose shorter wavelengths would permit even more data to be compressed into a given area, according to an article in July's Scientific American.