Yashchuk, V.; Lacey, I.; Arnold, T.; Paetzelt, H.; Rochester, S.; Siewert, F.; Takacs, P.: Investigation on lateral resolution of surface slope profilers. In: Lahsen Assoufid, Haruhiko Ohashi, Anand Asundi [Ed.] : Advances in Metrology for X-Ray and EUV Optics VIII : 11-12 August 2019, San Diego, California, United States. Bellingham, Wash.: SPIE, 2019 (Proceedings of SPIE ; 11109). - ISBN 978-1-5106-2912-7, p. 111090M/1-19
10.1117/12.2539527

Abstract:
We investigate and compare the spatial (lateral) resolution, or more generally, the instrument’s transfer function (ITF) of surface slope measuring profilometers of two different types that are commonly used for high accuracy characterization of x-ray optics at the long-spatial-wavelength range. These are an autocollimator based profiler, Optical Surface Measuring System (OSMS), and a long trace profiler, LTP-II, both available at the Advanced Light Source (ALS) X˗Ray Optics Lab (XROL). In the OSMS, an ELCOMAT-3000 electronic auto-collimator, vertically mounted to the translation carriage and equipped with an aperture of 2.5 mm diameter, is scanned along the surface under test. The LTP˗II ITF has been measured for two different configurations, a classical two-beam pencil-beam-interferometry and a single-Gaussian-beam deflectometry. For the ITF calibration, we apply a recently developed method based on test surfaces with one-dimensional (1D) linear chirped height profiles of constant slope amplitude. Analytical expressions for the ITFs, empirically deduced based on the experimental results, are presented. We also discuss the application of the results of the ITF measurements and modeling to improve the surface slope metrology with state-of-the-art x-ray mirrors. This work was supported by the U. S. Department of Energy under contract number DE-AC02-05CH11231.