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Interferometry of distant sources

  1. Feb 26, 2016 #1

    naima

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    When you try to get fringes, the worse is when the source is extended and the light has a large energy spectrum.
    With a star, the source seems pointlike. Is there another advantage as regards with bandwidth?
     
  2. jcsd
  3. Feb 26, 2016 #2

    Drakkith

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    What do you mean?
     
  4. Feb 28, 2016 #3

    naima

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    Suppose that an optical polychromatical signal is emitted at a given pointlike place during T. It has a coherence length there. When the signal propagates its shape changes and its Fourier transform too. If we measure the coherence length at a far distance of the souce, Is it the same?
     
  5. Feb 28, 2016 #4

    naima

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    I read that the coherence length of the light coming from a star is ##c/ \Delta \omega##
    What is the definition of this Delta? How is it measured?
     
  6. Feb 28, 2016 #5

    Drakkith

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    I'm sorry, I don't know much about this topic, but I'll try to help as best I can.

    If we're talking about broad-spectrum light, then I'm not sure there is a coherence length since the phase varies randomly.

    I think delta is given by the bandwidth of the emitted light. I'm not sure how this applies to the light emitted from a star, though.
     
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