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Interference in Thin Films

  1. May 4, 2014 #1
    1. The problem statement, all variables and given/known data

    Optical lenses (n=1.40) in cameras are coated with a thin film of magnesium fluoride (n=1.38) to reduce reflections. What minimum thickness is required to give minimum reflection at a wavelength of 550 nm?

    2. Relevant equations

    2nt = (lamda)/2

    3. The attempt at a solution

    I assume the relevant equation is what I'm supposed to use. so t=(lamda)/(4n)
    Therefore, the thickness of the film, t=550/(4*1.38)=99.6 nm

    I wasn't given the answer, so I'm not sure if this is correct. I wasn't sure what if the index of refraction of the camera was irrelevant information.
  2. jcsd
  3. May 4, 2014 #2
    I think they would rarely give irrelevant information in most coursework/homework questions, generally only happens if your lecturer wants to see you suffer)))
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