The direction of the macroscopic motion could be controlled by the polarization direction.
So light hits the group of molecules with a spectrum of energies (wavelengths) and polarization directions.
A polarization direction perpendicular is called s-polarized (s-polarised), accordingly.
The axes of the resulting ellipse are the resulting polarization directions.
When you add the two beams after this phase shift, the result is again a linearly polarized beam, but with a rotation in the polarization direction.
The phase difference between them as they exit the plasma causes the recombined linearly polarized wave to rotate its polarization direction.
Thus the polarization direction can be used to map out the galactic magnetic field.
In this case, the north-south axis is parallel to the polarization direction of the light that dissociated the ozone.
The cylindrical axis is the axis containing the polarization direction of the dissociating light.
Failure of rotational invariance: The light from the source might have a preferred polarization direction, in which case it is not rotationally invariant.
