Design and implementation of an x-ray reflectometer system for testing x-ray optics coatings

Abstract

We have developed an X-ray reflectometer (XRR) system for the characterization of various soft and hard X-ray optic coatings being developed at Marshall Space Flight Center. The XRR system generates X-ray radiation with a highoutput Rigaku rotating anode source (RAS), operational at a voltage range of 5 – 35 kV, a current range of 10-150 mA. A series of precision slits, adjustable down to approximately 25 micrometers, positioned in the beam path limit the extent of the x-ray beam and control the resolution of the XRR measurement while a goniometer consisting of two precision rotary stages controls the angular position of the coating sample and X-ray detector with respect to the beam. With the high count rate capability of the RAS, a very-high-speed silicon drift detector, the Amptek Fast Silicon Drift Detector (SDD), is implemented to achieve good count rate efficiency and improve reflectivity measurements of coatings at larger graze angles. The coating sample can be adjusted using a series of linear and tipping stages to perfectly align the center of the sample with the center of the incident X-ray beam. These stages in conjunction with the goniometer components are integrated through original control software resulting in full automation of the XRR system. We will show some initial XRR measurements of both single and multilayer coatings made with this system. These results and future measurements are used to characterize potential X-ray optic coatings culminating in the production of highly reflective coatings operational at a large range of X-ray energies.