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SPHERE (Spectro-Polarimetric High Contrast Exoplanet Research) is one of the first instruments which aim for the
direct detection from extra-solar planets. The instrument will search for direct light from old planets with orbital periods
of several months to several years as we know them from our solar system. These are planets which are in or close to the
habitable zone. ZIMPOL (Zurich Imaging Polarimeter) is the high contrast imaging polarimeter subsystem of the ESO
SPHERE instrument. ZIMPOL is dedicated to detect the very faint reflected and hence polarized visible light from
extrasolar planets. The search for reflected light from extra-solar planets is very demanding because the signal decreases
rapidly with the orbital separation. For a Jupiter-sized object and a separation of 1 AU the planet/star contrast to be
achieved is on the order of 10-8 for a successful detection. This is much more demanding than the direct imaging of
young self-luminous planets. ZIMPOL is located behind an extreme AO system (SAXO) and a stellar coronagraph.
SPHERE is foreseen to have first light at the VLT at the end of 2012. ZIMPOL is currently in the subsystem testing
phase. We describe the results of verification and performance testing done at the NOVA-ASTRON lab. We will give an
overview of the system noise performance, the polarimetric accuracy and the high contrast testing. For the high contrast
testing we will describe the impact of crucial system parameters on the contrast performance. SPHERE is an instrument
designed and built by a consortium consisting of IPAG, MPIA, LAM, LESIA, Fizeau, INAF, Observatoire de Genève,
ETH, NOVA, ONERA and ASTRON in collaboration with ESO.
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