How does a laser read a DVD?

Discussion in 'Archived Threads 2001-2004' started by Thik Nongyow, Aug 23, 2002.

  1. Thik Nongyow

    Thik Nongyow Stunt Coordinator

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    I hope I am not asking a technical question, but how does a laser read a DVD? Does a laser read a DVD like an LP or is it different?
     
  2. Kevin P

    Kevin P Screenwriter

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    This is a simplified explanation, but the information on a DVD (or a CD) is "pressed" into a reflective layer inside the DVD. This process creates microscopic "bumps" that reflect the laser light differently depending on whether it's a "one" or a "zero". As the laser passes over the track (which is a spiral going from the inner part of the disc to the outer part) it is reflected back into the lens where a sensor picks it up. The bumps cause variations in the amount of light reflected back from the disc, which is then decoded as "ones" and "zeros".

    In your question you asked if it's like reading an LP. Did you mean LP (as in vinyl records) or LD (as in laserdisc?) LPs are read with a stylus which transmits the vibrations to the cartridge which converts it into an electric signal. LDs are read by a laser similar to CDs and DVDs but they contain both analog and digital information instead of just digital information.

    KJP
     
  3. Eric C D

    Eric C D Second Unit

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    You might want to check out the following site:
    http://www.howstuffworks.com
    Specifically, in the followiung area:
    http://www.howstuffworks.com/dvd.htm
    There's also a good writup under analog and digital music to explain other parts of the process.
    I really enjoy the site when I have questions. Last thing I looked up was CAT scans.
    enjoy!
    Eric
    [edited because I found a better article!]
     
  4. Lew Crippen

    Lew Crippen Executive Producer

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