Polarizing mirrors for soft X-ray radiation

Periodic multilayer mirrors consisting of alternating layers of Fe/C, Ti/Ni or V/Ni have been produced at PSI by sputter deposition. The period has been chosen such that the first Bragg peak appears at the Brewster angle (Θ≈45°) if the energy of the radiation is close to the K edge of C or the L3 edges of Ti or V, respectively. The reflectances Rs and Rp of these mirrors in s- and p-polarization geometry have been measured with linearly polarized undulator light at BESSY II using the BESSY polarimeter. The maxima of Rs were 24% at 283 eV, 8% at 453 eV and 10% at 511 eV; the polarization efficiencies Rs/Rp showed maximum values >2000 in all three cases.