Polarized microscopy: exactly what does a retarder do?

rjlittlefield · Post by **rjlittlefield** » Mon Apr 23, 2012 1:39 pm

I read often about a "retarder" being used in polarized microscopy.

I have some feeling for what retarders do as a practical matter, but I'm very weak on the theory and I have not been successful at finding an explanation.

Can someone briefly explain and/or point to some helpful discussion? Thanks!

--Rik

Charles Krebs · Post by **Charles Krebs** » Mon Apr 23, 2012 2:03 pm

Rik,

Have you looked these over?

http://micro.magnet.fsu.edu/primer/tech ... shome.html

http://micro.magnet.fsu.edu/primer/tech ... plate.html

rjlittlefield · Post by **rjlittlefield** » Mon Apr 23, 2012 2:10 pm

No, I missed those, in addition to many other good references. The trick is to search on "retardation plate" rather than "retarder". Thanks!

--Rik

DQE · Post by **DQE** » Mon Apr 23, 2012 3:50 pm

A real long shot, more likely just thread clutter:

Is it possible that some of the optical retardation effects summarized in the links provided by Charles are active re the mysterious localized shifting of subject regions during stacking? This is the topic we've recently been discussing as Rik experiments.

The connection I am trying to make, probably without merit, is that interference and related optical effects are sometimes a part of some bugs' apparent external color creation schemes.

Thus, the mention of quarter-wave plate effects and the like got me to thinking that optical retardation etc may be active in creating the anomalous focus shifting seen by Rik during stacking.
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For convenience, here's the link to the (possibly) related recent thread by Rik (esp see page 2):

http://www.photomacrography.net/forum/v ... c&start=15

g4lab · Post by **g4lab** » Wed Apr 25, 2012 6:54 am

Rik
Google Ellipsometry

http://www.jawoollam.com/tutorial_1.html