ABSTRACT
The design of a versatile high-precision eight-axis ultrahigh-vacuum-compatible polarimeter is presented. This multipurpose instrument can be used as a self-calibrating polarization detector for linearly and circularly polarized UV and soft-x-ray light. It can also be used for the characterization of reflection or transmission properties (reflectometer) or polarizing and phase-retarding properties (ellipsometer) of any optical element. The polarization properties of Mo/Si, Cr/C, Cr/Sc, and Ni/Ti multilayers used in this polarimeter as polarizers in transmission and as analyzers in reflection have been investigated theoretically and experimentally. In the soft-x-ray range, close to the p edges of Sc, Ti, and Cr, resonantly enhanced phase retardation of the transmission polarizers of as much as 18 degrees has been measured. With these newly developed optical elements the complete polarization analysis of soft-x-ray synchrotron radiation can be extended to the water-window range from 300 to 600 eV.
ABSTRACT
We have systematically investigated ultrathin Cr/Sc multilayers (nanolayers), using tunable soft-x-ray synchrotron radiation. The multilayers were optimized for use either in normal incidence or at 45 degrees at photon energies around the 2p-absorption edges of Sc (399 eV) and Cr (574 eV), respectively. They were sputter deposited on Si wafers or on thin Si(3)N(4)-membrane support structures for use in reflection and in transmission, respectively, as polarizing and phase-retarding elements in a polarimeter. The performance theoretically expected with respect to reflection/transmission and energy resolution has been confirmed experimentally: A value of 7% for the normal-incidence peak reflectance at 395 eV was measured as well as a pronounced minimum in transmission for certain incidence angles and energies below the respective absorption edges, indicating significant phase-shifting effects.
