Characterization of linear polarizers in the wavelength 100-150 nm (VUV) for solar physics applications

VUV polarimetry has been recognized as one of the most powerful diagnostic tools for remote sensing of the solar corona, with the potential of providing accurate space resolved information on magnetic activity through observation of resonance lines of the most abundant species. In an on-going collaboration between our groups from Spain and Italy, a program to design, build and characterize optical components for the VUV region has been activated. In particular, using the beamline BEAR at the synchrotron facility Elettra in Trieste (Italy) we have characterized some thin film reflecting linear polarizers, designed and optimized for the study of polarimetric properties of the HI Ly-alpha at 121.6 nm. The characterizations are performed from 100 to 150 nm at different angles of incidence (40 - 80 deg). Some polarizers have shown excellent performances with an average reflectivity R ? 34% and a modulation factor exceeding 95%. The calibration of several samples is reported and aging effects on some old samples is discussed. One of the calibrated sample will be used for the evaluation of the performances of a new fast calibration set-up facility for VUV. © 2013 SPIE.