We start using depolarized processed data. About acquisition of polarized and depolarized Raman signals, see : "If the laser is linearly polarized, the majority of the Raman signal will be polarized in the same way", due to scattering events maintaining the polarization state. "A small fraction of the scattered light, however, will be polarized orthogonally with respect to the incident light. This is referred to as the depolarized signal". The ratio of depolarized and polarized signals (depolarization ratio) is providing information about the symmetry of a vibrational mode .