High precision soft x-ray reflectometer

At the radiometry laboratory of the Physikalisch-Technische Bundesanstalt (PTB) a reflectometer for the soft x-ray spectral region has been operated for several years utilizing monochromatic radiation of a toroidal grating monochromator or a high-resolution plane grating monochromator. The monochromators cover the photon energy region from 35 to 1500 eV. New challenges due to the development of soft x-ray optical components led to the design of a second reflectometer with advanced capabilities. Samples with a diameter of up to 250 mm can be accommodated. The time required for sample exchange is reduced by using a lock chamber. The feasibility of sample positioning with high precision has been improved. Typical uncertainties of about 1%–2%, e.g., for the reflectance of multilayer mirrors, can be achieved. A detailed description of the reflectometer as well as some typical results showing the performance are presented.