Polarization Aberrations in ZIMPOL High Contrast Polarimeter

Govaert, A. (2015) Polarization Aberrations in ZIMPOL High Contrast Polarimeter. Master's Thesis / Essay, Industrial Engineering and Management.

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Abstract

In polarimetry a high contrast between the unpolarized background and the polarized planet signal is crucial to the detection of exoplanets. Currently, small polarimetric aberrations dominate the ZIMPOL noise performance close to the central star, where exoplanet detection is most likely. This research deals with the accurate measurement of the polarimetric aberrations on component level and the modeling of birefringent wedges in the ZIMPOL retarders. It was found that all the polarization manipulating components in ZIMPOL introduce a sub-pixel differential shift between the modulation states of the instrument that is maximum when the two orthogonally polarized exit-beams have equal intensity. The analysis of the differential shifts show that the retarders introduce a beam deviation that is equal in magnitude and opposite in direction for orthogonal polarization components. In contrast to the phase, both the amplitude and period of the differential shifts can be explained by birefringent wedge angles in the crystal surfaces and optic axes. Empirical evidence shows that the differential shifts introduced by the individual components can be added to a combined effect with a fairly straight forward data reduction.

Item Type:	Thesis (Master's Thesis / Essay)
Degree programme:	Industrial Engineering and Management
Thesis type:	Master's Thesis / Essay
Language:	English
Date Deposited:	15 Feb 2018 08:09
Last Modified:	15 Feb 2018 08:09
URI:	https://fse.studenttheses.ub.rug.nl/id/eprint/13522

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