Preserving the coherence and wavefront of a diffraction limited x-ray beam from the source to the experiment poses stringent quality requirements on the production processes for X-ray optics. In the near future this will require on-line and in-situ at-wavelength metrology for both, free electron lasers and diffraction limited storage rings. A compact and easy to move X-ray grating interferometry (XGI) setup has been implemented by the Beamline Optics Group at PSI in order to characterize x-ray optical components by determining the aberrations from reconstructing the x-ray wavefront. The XGI setup was configured for measurements in the moire mode and tested with focusing optic at Swiss Light Source, Diamond Light Source and LCLS. In this paper measurements on a bendable toroidal mirror, a zone plate, a single and a stack of beryllium compound refractive lenses (CRL) are presented. From these measurements the focal position and quality of the beam spot in terms of wavefront distortions are determined by analysing the phase-signal obtained from the XGI measurement. In addition, using a bendable toroidal mirror, we directly compare radius of curvature measurements obtained from XGI data with data from a long-trace profilometer, and compare the CRL wavefront distortions with data obtained by ptychography.

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J. Krempaský, F. Koch, P. Vagovič, L. Mikeš, A. Jaggi, C. Svetina, U. Flechsig, L. Patthey, S. Marathe, D. Batey, S. Cipiccia, C. Rau, F. Seiboth, M. Seaberg, C. David, and U. H. Wagner, "Inspecting adaptive optics with at-wavelength wavefront metrology," Proc. SPIE 10761, Adaptive X-Ray Optics V, 107610D (Presented at SPIE Optical Engineering + Applications: August 21, 2018; Published: 18 September 2018); https://doi.org/10.1117/12.2320532.