Astronomical instruments dedicated to the study of Cosmic Microwave Background polarization are in need of optics with very low systematic effects such as beam shape and cross-polarization in an optical configuration. With the demand for millimetre wave larger focal planes comprising thousands of pixels, these systematic effects have to be minimal across the whole focal surface. In order to reach the instrument requirements such as resolution, cross-polarization and beam ellipticity, new optical configurations with well-understood components have to be studied. Refractive configurations are of great importance amongst the potential candidates. The aim is to bring the required technology to the same level of maturity that has been achieved with well-understood existing ones. This thesis is focused on the study of such optical components for the W-band spectral domain. Using optical modelling with various software packages, combined with the manufacture and accurate experimental characterization of some prototype components, a better understanding of their performance has been reached. To do so, several test set-ups have been developed. Thanks to these new results, full Radio-Frequency refractive systems can be more reliably conceived.

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