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Gaussian Beam Radius

  1. Oct 15, 2008 #1
    I'm doing FRAP(fluorescence recovery after photobleaching)
    Diffusion coefficient is what I wanna calculate.

    t:halftime of recovery fluorescence
    w:radius of the focused circular laser beam at the e^(-2) intensity
    f : correction factor for the amount of bleaching
    D:diffusion coefficient

    My question is how I can find w.
    I know this equation.

    I:Gaussian intensity profile
    For a circular disc profile, I=P/(pi*w^2)

    But I don't know exactly how to calculate w.

    Does anybody know this?? Please~~.
  2. jcsd
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