  In this diploma thesis, the calibration of the vector polarimeter POLIS will
be described. The instrument is built by the Kiepenheuer-Institut fuer
Sonnenphysik (Freiburg/Germany) in cooperation with the High Altitude
Observatory (Boulder/USA) and will be operated at the German Vacuum Tower
Telescope in Tenerife. The instrument yields simultaneously the polarization
state of light in two spectral ranges at 396 nm and 630 nm. The measurement is
performed with a rotating retarder, which modulates the incident polarization.
The modulation is transformed into a varying intensity through polarizing
beamsplitters. The demodulation uses a weighted integration scheme to obtain
the full Stokes vector of the radiation. The calibration of the polarimeter is
performed through the evaluation of a calibration data set produced with a
calibration unit consisting of a linear polarizer and a retarder. The
instrumental calibration and the polarimetric model of the telescope are
described in detail.
  This document is an unaltered version of my diploma thesis from 2002. Parts
of it have been re-used in later publications, but in a very compressed way
removing a lot of details. Its currrent intended use would be as introductory
literature to polarimetry and its application in solar physics for students. I
have used it a few times already for exactly this purpose.
