1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Fabry-Perot Etalon

  1. Mar 10, 2009 #1
    1. The problem statement, all variables and given/known data
    A certain spectral line is known to consist of two equally intense components
    with a wavenumber separation less than 20 m^-1: The Fabry-Perot fringes
    produced by this line are photographed, using a plate separation of 25 mm. The
    diameters of the smallest rings are found to be, in mm :
    1:82; 3:30; 4:84; 5:57; 6:60; 7:15:
    Explain why this experiment does not allow the wavenumber separation to be determined uniquely, but gives two possible values. What are they? Suggest a further experiment
    which could be carried out to resolve the ambiguity.

    2. Relevant equations
    Wavenumber FSR=1/2nd

    3. The attempt at a solution

    So I think this has something to do with the free spectral range? If you work that out with the above equation, assuming the etalon is in air, you get 20m^01. So as the wavenumber separation is less than this, fringes from the two different wavenumbers will overlap. But then I don't know how to get the two possible answers.

    Any help? Please?
  2. jcsd
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Can you offer guidance or do you also need help?
Draft saved Draft deleted