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Why aren't interference filters also polarizers?

  1. Jan 8, 2010 #1
    After all, the un-passed light reflects off a transparent medium with a definite index of refraction, right?
  2. jcsd
  3. Jan 9, 2010 #2


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    I think the only reason that you don't get significant polarisation is that the light strikes a polarising filter very near the Normal.
  4. Jan 19, 2010 #3
    ...Well, I did get one answer...

    Interference filters are poly chromatic, depending on viewing angle. Polychromatic, but not polarizing in any significant way.

    Anyone else?
  5. Jan 20, 2010 #4

    Andy Resnick

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    The filters I use (dichroics) have different efficiencies depending on the polarization of the incident light (s- or p- polarization), so I expect they can indeed polarize the incident light somewhat. The polarizing efficiency of the dichroic filter is much lower than a polarizer, tho.

    It's possible to design filters to have very high pass efficiencies for both the s- and p- states, so they would not induce any large amount of polarization.
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