Imaging polarimetry with the METIS coronagraph of the Solar Orbiter mission

METIS, the "Multi Element Telescope for Imaging and Spectroscopy", is a coronagraph of the Solar Orbiter mission to be launched in 2017. The METIS coronagraph includes three optical paths for i) broad-band imaging of the full corona in polarized visible-light (590-650 nm); ii) narrow-band coronal imaging in the UV HI Ly α (121.6 nm) and extreme-UV He II Ly α (30.4 nm), and iii) spectroscopic observations of the HI and He II Ly α. This presentation describes the optical design of the METIS visible-light path for imaging polarimetry of the K-corona. The achromatic polarimeter's requirements on polarization sensitivity, achromatic response and instrumental polarization control are described. The expected performances of the visible-light path are also presented.