Multilayer reflective polarizers for the far ultraviolet

Juan I. Larruquert; José A. Aznárez; Luis Rodríguez-de Marcos; José A. Méndez; A. Marco Malvezzi; Angelo Giglia; Paolo Miotti; Fabio Frassetto; Giuseppe Massone; Stefano Nannarone; Giuseppe Crescenzio; Gerardo Capobianco; Silvano Fineschi


Polarimetry in the far ultraviolet (FUV) is a powerful tool for the interpretation of the role of the coronal plasma in the energy transfer processes from the inner parts of the Sun to the outer space. FUV polarimetry from space provides more accurate observations on the kinetics of the features and on local magnetic fields through the Doppler and Hanle resonant electron scattering effects. Particularly interesting lines for FUV polarimetry are H Lyman α (121.6 nm) and β (102.6 nm), along with OVI lines at 103.2 and 103.8 nm. One key element to perform polarimetry measurements at these wavelengths is the need of efficient polarizers. A limitation of the available polarizers, such as crystal plates of MgF2 and LiF working at Brewster angle, is their moderate reflectance at the non-extinguished component of the electric field, which results in a modest polarizer efficiency.