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
Recent advancements in imaging techniques have enabled the detection of thousands of exoplanets, as well as the characterization of a multitude of protoplanetary disks. These disks are believed to...Show moreRecent advancements in imaging techniques have enabled the detection of thousands of exoplanets, as well as the characterization of a multitude of protoplanetary disks. These disks are believed to form planets, but have mostly been observed around low mass T Tauri stars. No observations of disks around high mass Herbig Be stars exist, raising the question whether planets and especially giant planets can form there. Using archival data from VLT/SPHERE/IRDIS, one of the world’s best direct imagers for exoplanets and protoplanetary disks, we have attempted to image the disk of such a Herbig Be star, MWC147 (alias V700 Mon & HD259431). For this data reduction, a variety of correction techniques are demonstrated and compared against each other. The resulting images reveal the prescence of a second companion, dubbed MWC147 C, and a large bow shaped structure. Furthermore, a model of VLT/SPHERE/ZIMPOL was designed to quantify the effects of instrumental polarization and crosstalk on the polarimetric efficiency of the instrument. Finally, an observing proposal for VLT/SPHERE was written with the goal of obtaining better data of MWC147, such that the bow shaped structure and disk of MWC147 could be better characterized.Show less
