Licenciate Thesis defense: Modelling optical systematics for current and next-generation CMB experiments

The polarization of the Cosmic Microwave Background (CMB) is at the centre of attention of the cosmological community, as the observable possibly offers a view of primordial gravitational waves. This effort faces two key challenges. The first is the impact of the Galactic contaminants on the cosmological signal, which may be tackled by telescopes with increased frequency and sky coverage. The second refers to systematics arising from the instrument itself. In this thesis, which focuses on optical systematics, I describe 1) the detailed time-domain simulations of a non-ideal polarization modulator, 2) the beam characterization of the Simons Observatory Small Aperture Telescopes.