A polarimeter to observe exoplanets

The work of this thesis is based on the study and the measurement of the polarization of exoplanets (a planet orbiting around a star different from the Sun). The first exoplanet was discovered in 1995. The new scientific challenge does not only consist in discovering new exoplanets, but it consist also in characterizing those already discovered. Theoretical studies highlight that polarimetry can be used for characterizing surface and atmosphere of the exoplanets. The aim of this thesis is to design a new kind of a polarimeter for characterizing exoplanets and to realize a prototype of the instrument. The optical scheme proposed for this polarimeter has never been used before. The polarimeter is projected to work in the visible light and near infrared wavelengths. The thesis has achieved the goal to provide a working prototype of the polarimeter. The polarimeter has been successfully calibrated with a small telescope and a source of artificial light in real operating conditions. A suited software has been developed to perform data analysis. Some preliminary observations of celestial bodies (stars, planets and satellites) have been performed. In particular, a series of observations of the Moon during different orbital phases have been made, verifying that the Moon's polarization is correctly modulated by orbital phase.