Re: strange pictures of lenses between crossed polarisers
- From: wadexkelman@xxxxxxxxxxx
- Date: 14 Mar 2007 17:08:00 -0700
On Mar 14, 5:57 pm, Andy Resnick <andy.resn...@xxxxxxxxxxx> wrote:
My understanding is that this effect is produced by differences in the
Fresnel transmission coefficients between S- and P- polarized light for
a surface, and azimuthally around the lens, the amount of linearly
polarized light has an angularly varying decomposition of S- and P-
components.
--
Andrew Resnick, Ph.D.
Department of Physiology and Biophysics
Case Western Reserve University
Yes, this is correct. I call it "skew polarization", but Moxtek, in
their excellent technical notes, calls it "geometric
depolarization". Here is a link to one of their papers:
http://www.moxtek.com/uploads/GEOMETRIC_DEPOLARIZATION.pdf
This effect can cause a loss of contrast if you are illuminating a
sample through a microscope with polarized light, and expect to remove
the lens' (specular) reflections by looking at the image through a
crossed polarizer. The incident light's polarization vector rotates
in a Maltese Cross manner with each lens it passes through, and the
specular reflections are thus not completely removed by the crossed
polarizer.
Wade Kelman
.
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