Spectroscopic polarimetry using channeled spectroscopic polarization state generator (CSPSG)

A novel method for the spectropolarimetric measurement of materials using the channeled spectrum is described. A pair of high order retarders are incorporated into the illuminating optics of a broadband spectropolarimeter, so that the sample under measurement is illuminated with the light that is modulated in the spectral-dependence of its polarization. The Fourier analysis of the channeled spectrum obtained from the spectropolarimeter allows determining the four spectrally-resolved polarimetric parameters of the sample simultaneously. This approach has a feature that it requires neither mechanically- nor electrically-controllable components for polarization modulation, similar to the previous method for the channeled spectropolarimetry in which the high-order retarders are placed in the receiving optics. The new method can offer the same information about the sample as has been obtained by the previous method, provided that all the optical components satisfy the principle of reciprocity. Furthermore, the new method has an additional advantage over the previous method that it is less susceptible to the sample-induced fluctuations of the wavefront or ray-direction. The effectiveness of this method is experimentally demonstrated with the measurement of a birefringent sample.