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Gouy Phase Shift

  1. Apr 18, 2012 #1
    Hello friends,
    Could you please explain me Gouy Phase Shift, i have gone through the wikipedia article and i know that it occurs because of the focusing although i am not able to get a physical picture of the same, so it would be really nice if anyone can explain me in simple words about this phenomenon.

  2. jcsd
  3. Apr 18, 2012 #2


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    That's a general phenomenon occuring at caustics. Usually, it is a good approximation to assume that the wave is a plane wave with wavevector given as k=nw/c, where w is the frequency, n the refractive index and c the speed of light in vacuum. Usually the intensity of that wave A varies slowly on a scale 1/k. This assumption breaks down near a caustic or a focal point and the intensity becomes very large over a distance [itex]\Delta x\approx \lambda/2=\pi/k[/itex]. This intensity bump thus shifts the phase of the wave after the focal point.
    A more careful analysis starts from the short wavelength asymptotics of the wave equation (WKB approximation), see e.g.:

    http://books.google.de/books?id=phb...wBzgo#v=onepage&q=caustic phase shift&f=false
  4. Apr 21, 2012 #3
    Thank you for your reply.
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