False signature reduction in channeled
spectropolarimetry

Abstract. Channeled spectropolarimetry measures the complete polarization state of light, using a single spectrum, by amplitude modulating the Stokes parameters onto spectral carrier frequencies. However, spectral features that are not band limited in the Fourier transform domain, such as narrow-band atomic absorption lines, can generate false polarimetric signatures. We present a false-signature aliasingreduction technique that reduces the error induced by these non-band-limited features. Additionally, the spectral resolution of the S0 Stokes parameter is improved, up to the maximum resolution offered by the spectrometer. A theoretical model for implementing the technique on a Fourier transform infrared spectrometer is presented, including an enhanced model that accounts for dichroism within the crystal. The approach is experimentally demonstrated in the middle-wavelength infrared 3–5 m with the use of two multiple-order yttrium vanadate retarders. Additional results demonstrating the technique for wavelengths spanning 2.5–15 m are obtained using cadmium sulfide retarders. Reconstructions are compared to conventional channeled spectropolarimetric reconstructions from the same system.

J. Craven and M. W. Kudenov, “False signature reduction in channeled spectropolarimetry,” Opt. Eng 49, 053602–053602 (2010).