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Homework Help: Superposition of two waves

  1. Feb 1, 2007 #1
    1. The problem statement, all variables and given/known data
    A magnetic-field technique for stabilizing a He-Ne laser to 2 parts in 10^10 has been patented. At 632.8 nm, what would be the coherence length of a laser with such frquency stability.

    2. Relevant equations
    Coherence time =1/delta frequency
    coherence length = c/delta frquency

    3. The attempt at a solution

    dont know what 10^10 stands for and how to solve this
    help would be much appreciated.
  2. jcsd
  3. Feb 1, 2007 #2


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    I think it means that the technique assures you that if you choose to give the laser a frequency f, then the actual frequency of the laser will effectively be f with an uncertainty of only ±(2*f*(10^-10)).

    See what I "did"? I shopped up f into 10^10 equal parts, then said that the uncertainty of f is 2 of those parts: 2*(f/[10^10])
    Last edited: Feb 1, 2007
  4. Feb 2, 2007 #3
    10^10 means 10 raised to the power of 10, which is 10 billion. So the frequency is stable to 2 parts in 10 billion.

    What is the frequency of the HeNe laser?
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