Linear Polarization Measurements with a New Soft X-Ray Polarimeter and Ellipsometer at a Bending Magnet Beamline of a Compact Storage Ring

Abstract

Linear polarization measurements were carried out using a newly developed soft x‐ray polarimeter and ellipsometer (SXPE) for complete polarization analysis at a soft x‐ray beamline (BL‐11) of the SR Center, Ritsumeikan University, Japan. A Mo/Si multilayer mirror (period: 10.36 nm, ratio of Mo layer to period: 0.64, and 23 bilayers with topmost Si layer) was deposited on the surface of a commercial Si(111) substrate by an ion beam sputtering method. It was cut into two pieces which were then used as reflection‐type polarizers. When the incident wavelength was scanned from 12.4 nm to 14.8 nm by a Monk‐Gillieson type varied‐line‐spacing grating monochromator of the BL‐11, the angles of incidence of both the Mo/Si multilayer polarizers in the SXPE were also varied from 37.5° to 52.3°. The polarizances depended strongly on the wavelength, and the best performance of over 99% was obtained in the vicinity of 14 nm. Using these polarizers, we assessed that the degree of linear polarization of the BL‐11 was almost constant at 85–88% in the measured wavelength range.