  We describe an experiment to measure calibration sources, the polarization of
Cosmic Microwave Background Radiation (CMBR) and the polarization induced on
the CMBR from S-Z effects, using a polarimeter, MITOPol, that will be employed
at the MITO telescope. Two modulation methods are presented and compared: an
amplitude modulation with a Fresnel double rhomb and a phase modulation with a
modified Martin-Puplett interferometer. A first light is presented from the
campaign (summer 2003) that has permitted to estimate the instrument spurious
polarization using the second modulation method.
