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.
Material science research in the soft-X ray regime at the Swiss Light Source accommodates five beamlines where the
monochromators rely on in-vacuum angular encoders for positioning mirror and gratings. Despite the factory-calibration
of the quadrature signals from these rotary encoders, the energy linearization for spectroscopic data requires accurate
calibration of the encoder quadrature signals. We characterize the interpolation errors and describe the Heydemann
correction algorithm for the quadrature signals for improving the energy linearization on a scale comparable with the
incremental encoder interpolation interval. Experimental data are shown where such errors produce sizeable effects in
soft-X ray spectroscopy and for which the correction algorithm efficiently improves the short-range non-linearity.
In the past few years a number of variable angle spherical grating monochromators (VASGM) have been proposed and installed at Elettra beamlines. At present one of them (ESCAmicroscopy beamline) is operating, two (Spectromicroscopy and GasPhase photoemission beamline) are under commissioning, and one (Circulary Polarized Light
beamline) is under construction. Although the experimental requirements of these monochromators are different, their control principles are the same. Approximately one year ago we started a project that aimed to provide a uniform and adequate system for controlling these monochromators. The paper deals with several frameworks of this project. First the monochromator software architecture is explained whereby the monochromator high level
application options are explained. Instead of using extensive look up tables for the relationship between the energy and the angles of the mirror and gratings, we tried to develop an on-line mathematical model for energy tuning. An interesting feature of this model is that all monochromator data are parametrized which is important for the
monochromator calibration. Much effort has been spent in order to understand the drive unit positioning behavior in the submicron scale which is non linear as a function of motor steps. As a result of this study some common drive unit mechanical properties were fixed according to which an absolute drive unit positioning control software is proposed. Finally we discuss some topics regarding the monochromator calibration and resolution optimization.