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Laser beam

  1. Jul 2, 2008 #1
    Information is stored in a series of pits on the disc. These pits are scanned by a laser beam. An significant limitation on amount of information that can be stored on a disc is width of laser beam.

    I knew why the width of laser beam is important coz diffraction effect of loght.

    How using shorter-wavelength laser allows more information to be stored on disc of same size??

    Any website i can refer to ??? Thanks!!
  2. jcsd
  3. Jul 2, 2008 #2


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    Well for one, decreasing the wavelength of the light, allows to decrease the size of the pits, hence more will fit on a line of given length.
  4. Jul 4, 2008 #3
    Also don't forget that "pressed" discs have two layers, by increasing the laser power, it is possible to trasmit through the first layer onto the second layer.

    Try looking for DVD under wikipedia:


    and "how stuff works":


    Also Note that information is limited in 2d space (ok it is quasi 3d space, since we have two layers)
    Future data storage is working on holographic 3d data storage (which is still optical based):



  5. Jul 7, 2008 #4
    I was aware that it had to do with diffraction patterns that determined how much data. The shorter the wavelegth, the closer the (spiral) of information is on the disc.
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