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CD and DVD

CD and DVD. How CD and DVD works By: Mark Jiang. History of the Compact Disk. Compact disk (CD) started in the 1970’s with the videodisk in the form of Video Long Play (VLP) read-only systems. In 1982 the CD-DA (compact disk-digital audio) was introduced to the market.

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CD and DVD

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  1. CD and DVD How CD and DVD works By: Mark Jiang

  2. History of the Compact Disk • Compact disk (CD) started in the 1970’s with the videodisk in the form of Video Long Play (VLP) read-only systems. • In 1982 the CD-DA (compact disk-digital audio) was introduced to the market. • In 1985, the technology was extended to computer storage as CD-ROM (compact disk-read only memory). • In November of 1996 the high-density compact disk DVD (Digital Versatile Disc) was introduced to the market.

  3. CD: Material • Polycarbonate Plastic • Aluminum • Acrylic • Label

  4. CD: Spiral • A CD has a single spiral track of data, circling from the inside of the disc to the outside. • the picture on the right does not show how small the data track is, it is approximately 0.5 microns wide, with 1.6 microns separating one track from the next. (A micron is a millionth of a meter.) And the bumps are even smaller.

  5. CD: Spiral • Low-magnification (X32) image of a CD showing an edge of the data zone.

  6. CD: Bumps • The bumps are each 0.5 microns wide, a minimum of 0.83 microns long and 125 nanometers high. (A nanometer is a billionth of a meter.) We often call it "pits" on a CD instead of bumps.

  7. CD: Pits • How Small are the Pits?

  8. Did You Know? • The incredibly small dimensions of the bumps make the spiral track on a CD extremely long. If you could lift the data track off a CD and stretch it out into a straight line, it would be almost 3.5 miles (5 km) long!

  9. DVD: Different Types

  10. DVD versus CD

  11. CD Drive: Components

  12. How CD Drive Read Data: Optics

  13. How CD Drive Read Data: Surface The laser beam (wavelength ~ 780 nm) is focused onto the data side of the disk (focused spot diameter ~ 1mm).

  14. How CD Drive Read Data: Laser Focus

  15. How CD Drive Read Data: Tracking

  16. How CD Drive Read Data: Tracking

  17. CD Drive: Motor

  18. VIDEO

  19. ENDThank You • Information From: • HowStuffWorks • http://www.howstuffworks.com/cd.htm • M. Mansuripur • Optical Sciences Center • The University of Arizona Tucson

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