Analysis of phase measurements in combined interferometer and polarimeter systems

Combined interferometer and polarimeter systems, using a single detecting e lement per line of sight, are susceptible to perturbation of the interferom etric phase when modulation of the polarization vector is applied. This iss ue has been investigated extensively for the case of a rotating ellipticall y polarized probing beam, demonstrating that here a perturbation is inevita ble. In this article the analogy between this analysis and earlier work is pointed out, and the underlying physics discussed. It will be demonstrated that schemes have been proposed in which the perturbation has been avoided or kept well within acceptable limits.