Patent Number: 
Section: claims

1. An X-ray optical device, comprising:an X-ray source configured to emit X-rays;an X-ray optics configured to image a beam of X-rays generated by the X-ray source onto a sample to be analyzed;a beam blocking unit arranged for selectively blocking off at least a portion of the X-ray beam output by the X-ray optics;the beam blocking unit comprising a rotating shaft and a beam blocking element, wherein the rotating shaft is rotatable by a driving unit around a rotating shaft axis and arranged laterally offset with respect to the X-ray beam output by the X-ray optics;wherein the beam blocking element is mounted eccentrically on the rotating shaft such that the beam blocking element is movable into different beam overlap positions for blocking off corresponding portions of the beam when the beam blocking element is eccentrically rotated around the rotating shaft axis;a sensor unit configured to measure an angle of rotation or angular position of the shaft rotated by the driving unit; anda control unit, wherein the control unit is in communication with the sensor unit, the driving unit and an external input device, wherein the control unit is configured to:determine an actual beam overlap position of the beam blocking element based on the angular position of the rotating shaft measured by the sensor unit;compare the actual beam overlap position with a set beam overlap position received from the input device; andbased on the comparison, generate a signal that controls the driving unit to drive the rotating shaft to an angular position that corresponds to the set beam overlap position. 2. The X-ray optical device according to claim 1, wherein the beam overlap position of the beam blocking element depends on the angle of rotation of the rotating shaft. 3. The X-ray optical device according to claim 1, wherein the beam blocking element is movable into any position between a predetermined minimum overlap position and a predetermined maximum overlap position by selecting a corresponding angle of rotation between 0° and 180°. 4. The X-ray optical device according to claim 1, wherein the beam blocking element is movable from a minimum overlap position to a maximum overlap position and from the maximum overlap position back to the minimum overlap position by turning the rotating shaft one full revolution. 5. The X-ray optical device according to claim 1, wherein the beam blocking element comprises a rotationally symmetric body with a lateral surface defining a beam blocking edge for the X-ray beam. 6. The X-ray optical device according to claim 1, further comprising:a bearing unit designed for rotatably bearing the rotating shaft; anda casing designed for receiving the bearing unit, the rotating shaft and the beam blocking element. 7. The X-ray optical device according claim 1, further comprising at least one sealing element designed for realizing an air-tight seal around the rotating shaft. 8. The X-ray optical device according to claim 1, wherein the driving unit comprises an electric motor configured to generate a torque and a belt drive configured to transmit the torque to the shaft. 9. The X-ray optical device according to claim 1, wherein the X-ray optics comprises at least one reflective element designed to image an X-ray beam with a predetermined focal length. 10. The X-ray optical device according to claim 1, further comprising a collimator configured to further refine the beam of X-rays in between the X-ray optics and the sample, wherein the beam blocking unit is either arranged after the X-ray optics, before the collimator or after the collimator. 11. A method of operating an X-ray optical device, the method comprising the steps of:generating X-rays by an X-ray source;imaging, by the X-ray optics, a beam of the X-rays from the X-ray source onto a sample to be analyzed;collimating, by a collimator, the beam of X-rays to be imaged to the sample, the collimator located between the X-ray optics and the sample;adjusting a divergence angle or intensity of the imaged X-ray beam in dependence of the sample to be analyzed, wherein the adjusting step comprises moving a rotating shaft and a beam blocking element towards a desired overlap position by rotating the rotating shaft by a predetermined angle of rotation, wherein the adjusting step is performed automatically by a control unit and a driving unit which is mechanically coupled to the rotating shaft. 12. An X-ray analysis system configured to analyze crystalline or powder samples, the system comprising:an X-ray source configured to emit X-rays;an X-ray optics configured to image a beam of X-rays generated by the X-ray source onto a sample to be analyzed;a beam blocking unit arranged for selectively blocking off at least a portion of the X-ray beam output by the X-ray optics;the beam blocking unit comprising a rotating shaft and a beam blocking element, wherein the rotating shaft is rotatable by a driving unit around a rotating shaft axis and arranged laterally offset with respect to the X-ray beam output by the X-ray optics;wherein the beam blocking element is mounted eccentrically on the rotating shaft such that the beam blocking element is movable into different beam overlap positions for blocking off corresponding portions of the beam when the beam blocking element is eccentrically rotated around the rotating shaft axis;a sensor unit configured to measure an angle of rotation or angular position of the shaft rotated by the driving unit;a control unit, wherein the control unit is in communication with the sensor unit, the driving unit and an external input device, wherein the control unit is configured to:determine an actual beam overlap position of the beam blocking element based on the angular position of the rotating shaft measured by the sensor unit;compare the actual beam overlap position with a set beam overlap position received from the input device; andbased on the comparison, generate a signal that controls the driving unit to drive the rotating shaft to an angular position that corresponds to the set beam overlap position;a sample stage configured to hold and orient the sample to be analyzed relative to the X-ray beam output by the X-ray optical device; andan X-ray detector configured to detect X-rays scattered by the sample. 13. The system according to claim 12, wherein the beam overlap position of the beam blocking element depends on an angle of rotation of the rotating shaft. 14. The system according to claim 13, wherein the beam blocking element is movable from a minimum overlap position to a maximum overlap position and from the maximum overlap position back to the minimum overlap position by turning the rotating shaft one full revolution. 15. The system according to claim 12, wherein the driving unit comprises an electric motor configured to generate a torque and a belt drive configured to transmit the torque to the shaft. 16. The system according to claim 12, further comprising a collimator configured to further refine the beam of X-rays in between the X-ray optics and the sample, wherein the beam blocking unit is either arranged after the X-ray optics, before the collimator or after the collimator.