In order to improve the the polarimetric performances of VLT’s SPHERE/ZIMPOL polarimeter instrument, polarization dependent beam shifts due to reflection of a coated aluminum mirror need to be...Show moreIn order to improve the the polarimetric performances of VLT’s SPHERE/ZIMPOL polarimeter instrument, polarization dependent beam shifts due to reflection of a coated aluminum mirror need to be taken into account. Therefore measurements are performed to characterize these beam shifts using a cylindrically shaped beam. In plane-of-reflection beam shifts, as described by the Goos-Hänchen effect, and out of plane-of-reflection beam shifts, described by the Imbert-Federov effect, have been measured. A measurement setup has been built which measures relative beam shifts of orthogonal polarizations states for different angles of incidence. Using the measurements of the Goos-Hänchen effect a beam shift is detected in the plane-of-reflection, where no shift in out of the plane-of-reflection is detected. An effective refractive index of n = 1.12 and k = 2.57 has been found. Measurements of the Imbert-Federov effect show a significant shift out of the plane-of-reflection, where no shift is detected in the plane-of-reflection, yet a complex refractive index could not be determined.Show less