Calibration of Stokes polarimeters with liquid-crystal variable retarders using the measured intensities

In this work, three previously published configurations of a Stokes polarimeter using two liquid-crystal variable retarders are studied. All three configurations are optimized in terms of the condition number, κ, of the characteristic matrix, by assuring that κ=3. The polarimeters are calibrated using a novel method incorporating the variations of the measured intensities for known samples, half-wave retarders, and quarter-wave retarders. It is found that the proposed calibration improves on a previously published, non-linear fitting method, as it gives very similar results for all three polarimeter configurations proposed. The results obtained also have a slightly smaller overall error than the best case with the previously published method. In addition, the proposal is simpler to implement and is a very stable and robust method.