Spectral THz ellipsometer for the unambiguous determination of all Stokes parameters

We present a new THz ellipsometer concept by which all Stokes parameters can be determined without the need of a retarder as a phase shifting device. The concept is based on an interferometer of the Martin-Puplett type and was tested below 1.5 THz employing synchrotron radiation from a bending magnet (dipole) as a radiation source.