Depolarization of microwaves in electromagnetic polarimetry: Influence, detection, and measurement

Precise polarimetric measurement with microwaves is taking on a growing interest (in plasmas and ferroelectricity, as well as Faraday, Cotton-Mouton-Voigt, Kerr, and other effects) and it is for this reason that the present author draws attention to the fact that in order to make meaningful measurements of rotation and ellipticity, account must be taken of the possible depolarization of waves. It is demonstrated that the measurement of wave depolarization can be made with the aid of a two-wave interference depolarimeter and polarimeter-ellipsometer used in conjunction with a single detector. Thus, point-by-point measurements are conducted which give simultaneously depolarization, rotation, ellipticity, and the sign of the ellipticity. It is shown that a depolarimeter and polarimeter-ellipsometer using a three-wave interferential analyzer can also be used to obtain all these values, and in addition can record their variations, which is indispensable for the study of unstable phenomena, or for a too rapid evolution where point-by-point measurements cannot be made.