|Goodwin, Michael. Digital Audio CD and Other Selected Technology Based on Principles of Digital Audio 4th Edition by Ken C. Pohlman and Other Sources, 2002.||NA (numerical aperture) and wavelength also determine track pitch (average distance between tracks: 1600 nm for CD and 740 nm for DVD), cutoff frequency and ultimately disk playing time.||0.74 µm|
|DVD. Britannica Online.||DVD players use a higher-power red laser (0.65 µm) that enables smaller pits (0.4 µm) separation tracks (0.74 µm) to be used||0.74 µm|
|Optical Opulence: The Sight and Sounds of DVD, Smart Computing. Vol. 4, No.3, Aug 2000.||The distance between tracks on DVD media is mere 0.74 microns while the distance between tracks on a CD media is 1.6 microns.||0.74 µm|
|Darvin, Vyacheslav. 3 Dimension Disc, no date.||
Nowadays, we can throw out our videocassette tapes and replace it with a slim disk that provides better quality of the video we want to se. This slim disk is known as the digital videodisc, DVD. The companies Phillips and Sony invented DVDs n the year 1995. It is recent useful innovation that is similar to compact disks (CD). DVDs provide better viewing of videos and has better audio quality. It also has more storage capacity and DVD drives are faster than current CD drives. When DVDs were first introduced, DVDs were made to store up 4.7 gigabytes of data. It has a round shape and a fixed disc diameter of 120 mm. Its optical system has a wavelength between 635-650 nm and the separation between the tracks on a DVD is 0.74 µm.
DVDs are used to store different types of movies one would like to watch. Nowadays, there are millions of videos around the world based on adventure, comedy, romance, etc. IF you want any kind of DVDs, you could just purchase it from a local video store instead of purchasing chunky videocassette tapes that don't show great quality like DVDs.
Amy Wu -- 2002