I wasted a few weeks of time by making the wrong searches, I just looked for stuff related to so called Kerr microscopes and all I found every time was that the polarization of the reflected light was rotated. So that was always about linear polarization because it makes not much sense to ‘rotate’ light that is circular polarized. Ok there are of course also all kinds of elliptic polarized photons and there it might make some sense to talk about rotation of polarization but in fact those Kerr microscopes all work (as far as I know) all with linear polarization. And there is nothing wrong with that, I mean it is not forbidden or so but I wanted to see how the visibility of magnetic domains is using circular polarized light. And when I finally searched for that (visibility of magnetic domains using circular polarized light) within a minute or five I got what I wanted.

Let me very short describe what I expected and how I think it all works:
1) Electrons are magnetic monopoles and as such there are two kinds of them. 2) The photons produced by these two types of electrons have their magnetic field phase shifted by 180 degrees. 3) The way these photons react on other electrons depends on what kind of electron it is. Therefore you should see a difference for neighboring magnetic domains in a material that has magnetic domains. Furthermore the magnetic domains have surpluses of one kind of electrons and a deficit of the other kind of electrons. So that’s 4) Domains have surpluses of one kind. And, also very important, the domain walls keep these surpluses/deficits as they are. So if a domain has a surplus of say north pole like like electrons or n-electrons as I name them in the post below, the n-electrons get repelled by the domain wall.

So what are we going to see if we shine a circular light source on a piece of condensed matter that has magnetic domains (I think the authors used a film or a flat kind of material)? I will link my source file below but first we take a look at the four pictures that make up this new post:

As you see the results are very similar but also very different. If you use a standard setup for a Kerr microscope with linear polarized light and also use a so called analyser, that jacks up the contrast. And with using circular polarized light you get a much more subtle picture. What I found very interesting is that the domain walls become darker so that more or less confirms domain walls repel unpaired electrons.

Ok, all that’s left is the source file link:

Analyzer-free, intensity-based, wide-field magneto-optical microscopy
Link used: https://pubs.aip.org/aip/apr/article/8/3/031402/124820/Analyzer-free-intensity-based-wide-field-magneto

I think the time has come to end this post, thanks for your attention and may be see you around in a new post.