Ly-alpha polarimeter design for CLASP rocket experiment
  A sounding-rocket program called the Chromospheric Lyman-Alpha Spectro-Polarimeter (CLASP) is proposed to be launched in the summer of 2014. CLASP will observe the solar chromosphere in Ly-alpha (121.567 nm), aiming to detect the linear polarization signal produced by scattering processes and the Hanle effect for the first time. The polarimeter of CLASP consists of a rotating half-waveplate, a beam splitter, and a polarization analyzer. Magnesium Fluoride (MgF2) is used for these optical components, because MgF2 exhibits birefringent property and high transparency at ultraviolet wavelength. 
H. Watanabe, N. Narukage, M. Kubo, R. Ishikawa, T. Bando, R. Kano, S.   Tsuneta, K. Kobayashi, K. Ichimoto, J. Trujillo-Bueno
astro-ph.IM astro-ph.SR physics.optics