Excellent description of polarized light for use in microscopy.
Larsen, Griffin, Grabel, Witte, Axer. Polarized Light Imaging of White Matter Architecture. Micro Res Tech 70:851–863 (2007)
Start reading at section titled "Static Crossed-Polars".

Note the bilateral symmetry in a slice of mouse brain imaged by Nomarksi optics.

Plan for crossed pol with AxioZoom microscope.