Polarization performances of mica crystal polarizers in 1-keV region

Imazono, Takashi; Hirono, Toko*; Kimura, Hiroaki*; Saito, Yuji  ; Muramatsu, Yasuji*; Sano, Kazuo*; Ishino, Masahiko; Koike, Masato

An experimental evaluation for the state of polarization of soft X-ray in the 1-keV region between 0.7 and 1.9 keV has not been performed because there is no polarizing element suitable for this energy region. In order to evaluate the state of polarization of polarized soft X-ray in the 1-keV region, we have developed a reflection-type polarizer by use of fluorophlogopite mica crystal which has the lattice constant of approximately 1 nm and can be made large single-crystal in these days. The polarization performance of fluorophlogopite mica was evaluated by the rotating-analyzer method at the BL23SU beamline, which was tuned to horizontal linear polarization mode, of SPring-8. As the result, the reflectance for s- (p-) polarization and the polarizance of fluorophlogopite(002) was 2.6% (0.013%) and 0.998 at the incident angle of 45.02 at 0.88 keV, respectively. This indicates that fluorophlogopite mica works the high efficient reflection-type polarizer. Using it, the degree of linear polarization of the incident light at 0.88 keV was determined. The polarization performances of muscovite and phlogopite micas are also mentioned.