Reflectometer with spectrometer-monochromator RSM-500

This reflectometer is designed for operational testing of X-ray optical elements of arbitrary shape with a maximum diameter of 300 mm. It consists of a radiation source module, a RSM-500 spectrometer-monochromator and a goniometer chamber. The radiation source is a detachable X-ray tube with replaceable anodes, which allows for rapid switching between wavelengths. A spherical diffraction grating is used as a spectral element in the RSM-500. Spectral resolution in the EUV range is λ/δλ≈380. Depending on the radiation range of interest, spherical gratings with curvature radii of 6 m (range 0.6-5 nm), 4 m (range 1.6 – 9 nm) and 2 m (range 4 -50 nm) are used. Polychromatic radiation from a source (X-ray tube) falls through an entrance slit onto a diffraction grating, after which, in accordance with the grating equation:

where m is the diffraction order, λ is the wavelength and D is the grating period, α and β are the angles of incidence and diffraction, respectively, monochromatic radiation is focused on the exit slit of the spectrometer. Then the diffracted beam is directed through the exit slit to a toroidal mirror, focusing the radiation on the sample under study, fixed on the goniometer. The reflected radiation is recorded by a detector based on a secondary electron multiplier of the SEM. Anti-scattering horizontal and vertical diaphragms serve to reduce scattered radiation in the spectrometer, as well as to limit the vertical probe beam.

External appearance of the reflectometer with a spectrometer-monochromator RSM-500

Schematic diagram of a high-resolution laboratory reflectometer based on RSM-500