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Holographic dispersion

  1. Jun 11, 2003 #1
    I have read that the interference patterns on a piece of holographic film can be cut, and any segment that is cut out will display the entire hologram when a laser is used to produce an image. By this I mean if you take a piece of holographic film and cut out any portion of it, that portion, no matter where it is taken from, can be used to produce the full hologram (however the smaller the portion the more fuzzy the hologram will be that is produced). Does anyone know how the interference waves on a piece of holographic film produce a three d image? Does anyone know how it can be that any piece of the film can be used to reproduce the whole image? I know a laser beam is split and one part of the beam goes to the image and the other part of the beam goes to the film, a mirror is used somewhere or somehow......

    Really what I would appreciate is someone explaining to me how a three dimensional holographic image is created and produced and if possible to also answer the question concerning how a part can display the whole. . .

    There is a book called the Holographic Universe which is where i am getting what i know about holograms from. Has anyone read it? In it the book discusses how the universe might be one huge hologram, but i forget why this suggestion has been made. If anyone can elaborate on this subject I would greatly appreciate it.
     
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  3. Jun 11, 2003 #2

    Integral

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    A hologram captures a difraction pattern. This pattern is the sum total of all light which passes through the film plan, or the plane directly in front of your cornea. Consider the plane directly in front of your cornea, each point in that plane recieves light information from every point which can be seen. So every point in the plane has ALL of the information necessary to see the "scene". This is the information which is captured by a hologram. And that is why you can indeed see the entire "picture" with any fragment of a hologram. Naturally if the hologram is on Silver Halide film this is only true above the grain (or pixel)size.

    Lenes are analog computers for tranforming difraction patterns to images.
     
  4. Jun 12, 2003 #3
    Every peice of the hologram can recreate the entire hologram? this dosn't seem right. If I had a hologram, and for simplicity we cut it into 4 quadrants like a catesian plane, isn't it true that when looking at quadrant 3 we see the entire picture still, but from quadrant 3's perspective (such that no matter how we looked at it, we won't see the picture as from the perspective of quadrant 1)? Or does each peice now become the same hologram 1/4 the size?
     
  5. Jul 31, 2003 #4
    What 'On Radioactive Waves' says is correct. When you fragment a holographic plate or film, you can indeed see the entire object scene but only from that fragment's points of view. I have read that book as well, but they neglect to mention that. I read an interesting analogy some were on the web and will try to reconstruct it. Think of a window in your house looking out on a tree in the yard. Just because one day you decide to board up half of the window doesn't mean you still can't see the tree, but indeed your potential povs are more limited.
     
  6. Jul 31, 2003 #5

    Integral

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    Don't get to caught up in that change in view point. How much does a scene chage if you move a inch?
     
    Last edited: Jul 31, 2003
  7. Aug 2, 2003 #6
    As far as both information and interference are concerned, quite a bit. Never the less, I believe even the smallest details should never go unmentioned unless explicitely stated why they are not.
     
  8. Aug 2, 2003 #7

    Integral

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    Be sure you understand the basics before getting mired in the 2nd order effects. Especially when the basics contain the 2nd order. If you understand that a hologram is the total difraction pattern for a particular plane in space your observation is coverd.
     
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