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HVD: Holographic Versatile Disc

  1. Dec 8, 2006 #1
    Has anyone here heard about the new data storage medium that is being researched? Apparently it'll be able to store up to 3.9 terrabytes of data, which is insane.

    Anyway, I checked out this article on Wikipedia to see how it worked...


    ...and I don't quite get it.

    Here's what I can gather... there are two layers on the HVD, one which is read by red laser light and contains 'servo' data, and above this is a layer with normal data on it, read by a green-blue light. The red light passes through the normal data layer, so there's no interference or other weirdness.

    But what I don't get it... how does simply storing servo data on a seperate layer manage to free up 3.9 TERRABYTES of data? The green-blue light has a longer wavelength than the blue laser light used to read Blu-ray discs, and they can't store anything near the amount as HVDs will.

    So what's going on? And what *exactly* is servo data?
  2. jcsd
  3. Dec 11, 2006 #2


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    Gold Member

    Your answer lies in the very first paragraph of the Wiki article:

    It would seem to me that the advantage of having the servo information on a different layer is it doesn't take up space on the data layer, making it possible to store more "real" data on a layer.
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