Since the data is compressed into smaller areas, the track pitch is reduced to 0.74 microns, which is less than half that of CDs, which is 1.6 microns. The minimum pit length is only 0.4 microns compared to 0.83 microns on an average CD. An average DVD holds about 4 times the number of data pits that can be held by a CD. The error correction of a DVD is also very organized and efficient as compared to a CD. Thus more information can be contained in the area reserved for error correction, further expanding the storage capacity of a DVD.
Due to the smaller size of DVD pits, the laser also has to be made smaller. The wavelength of a DVD laser has also been reduced. At about 350 nm, the beam is smaller and more accurate than that which can be found inside a CD player. The smaller beam also gives no problems when reading bigger pits. Therefore a DVD player can also be used to read CDs.
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