Figure 1.

Maps of the Mueller polarimetry parameters [(a) Azimuth $\alpha$ (in ${}^{\circ }$), (b) retardance R (in ${}^{\circ }$), (c) depolarization $\mathrm{\Delta }$] for two of our 9 samples, chosen for their different initial mean azimuth $<\alpha >$ (top—Sample 1, $⟨\alpha ⟩\approx {150}^{\circ }$; bottom—sample 8, $⟨\alpha ⟩\approx {80}^{\circ }$; direction of traction $0^{\circ }$).