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Why do DVDs use red lasers instead of the infrared lasers used in audio CDs?
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laser
Basic laser components.
DVDs utilize red lasers instead of the infrared lasers found in audio compact discs to achieve significantly higher storage density.12
Because red light has a shorter wavelength than infrared light, the laser beam can be focused more precisely to read much smaller data pits on the disc's surface. This increased precision allows a DVD to store the vast amount of information required to play a full-length motion picture, whereas the larger spots read by infrared lasers limit the capacity of standard audio CDs.12
This principle of using shorter-wavelength light to enable higher data density continues with newer technologies, such as Blu-ray, which employs blue-light lasers to store even more information in the same physical space.1