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Homework Help: Fabry Perot Interferometer

  1. Jan 31, 2014 #1
    Design a Fabry perot interferometer, that provides a transmission of T =1 for light with λ1 = 499nm under orthogonal incidence and a transmission for λ2 = 500nm of T≤0.01 (without any further maxima in between). How big has to be the finesse?

    Draw the transmission curve of several Fabry - Perot interferometer with this particular geometry (i.e. the same optical path length) for different finesse - values of F-1, 10 and 100 in the range from 498 nm to 501nm.
  2. jcsd
  3. Jan 31, 2014 #2


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    hello Ayesha,

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  4. Jan 31, 2014 #3
    I have tried to solve the above question in the following way:

    T = 1 for λ1 = 499nm

    T ≤ 0.01 for λ2 = 500nm

    for orthogonal incidence : Δs = 2nd, n = 1

    Δs = m (λm)

    m=1; n=1

    d= λ1/2 = 249.5 nm

    and i couldn't solve further...

    Please help :)
  5. Jan 31, 2014 #4


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    It will be difficult to build such an instrument. 249.5 nm is too small, and a deviation of +0.5 nm would already let the 500 nm through with the same T. A hair is 50 μm !

    You need an expression for the transmission of such a thing as a function of the wavelength. Nicely to be accomodated under 2): relevant equations...
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