The effect of alignment errors in polarimetry of light using liquid-crystal variable retarders

Experimental results using Liquid-Crystal Variable Retarders (LCVRs) to measure the four Stokes parameters of a light beam simultaneously are presented. We use known waveplates (half-wave and quarter-wave) as known sources to provide controlled polarization states to the Stokes polarimeter, and we use the measured Stokes parameters as functions of the orientation of the axes of the waveplates as an indication of the quality of the polarimeter. The effects of errors in optical alignment and nonlinearity of the retardance variation on the results are presented and discussed. We also present results of simulations for comparison. Finally, we present the advances obtained in the development of a Mueller matrix polarimeter for use in a goniometric scatterometer.