Patent Number: 
Section: claims

1. An X-ray optical element for collimating an X-ray beam, the element comprising:a Soller slit having an axis defined by a plurality of lamellas, said lamellas collimating the X-ray beam with respect to a direction of said axis; anda collimator for delimiting the X-ray beam, said collimator being rigidly connected to said Soller slit during operation of the optical element, wherein the X-ray beam delimited by said collimator intersects said axis of said Soller slit within said Soller slit, a direction of the X-ray beam thereby subtending an angle α≧10° with respect to said axis of said Soller slit. 2. The X-ray optical element of claim 1, wherein said Soller slit is a linear Soller slit. 3. The X-ray optical element of claim 1, wherein said Soller slit is a radial Soller slit. 4. The X-ray optical element of claim 2, wherein said lamellas of said linear Soller slit are disposed parallel to a direction of the X-ray beam delimited by said collimator. 5. The X-ray optical element of claim 1, wherein said Soller slit has a recess perpendicular to said Soller slit axis. 6. The X-ray optical element of claim 1, wherein said Soller slit comprises two partial slits, wherein said collimator is at least partially disposed between said two partial slits. 7. The X-ray optical element of claim 1, wherein said collimator has at least two collimator jaws, said collimator jaws being disposed on different sides of said Soller slit. 8. The X-ray optical element of claim 7, wherein said collimator jaws subtend an angle with respect to said axis of said Soller slit which differs from 90° or an angle of 45°. 9. The X-ray optical element of claim 1, wherein said collimator is disposed on one side of said Soller slit. 10. The X-ray optical element of claim 9, wherein said collimator is made in one piece. 11. The X-ray optical element of claim 1, wherein said collimator is made from tantalum. 12. The X-ray optical element of claim 1, wherein a geometry of said collimator or of a collimator opening in said collimator can be adjusted in a non-operating state. 13. The X-ray optical element of claim 1, wherein said collimator is a further linear Soller slit. 14. The X-ray optical element of claim 13, wherein said Soller slit is a linear Soller slit, said linear Soller slit and said further linear Soller slid having different divergence angles. 15. The X-ray optical element of claim 1, wherein said collimator is a further radial Soller slit. 16. The X-ray optical element of claim 15, wherein said Soller slit is a radial Soller slit, said radial Soller slit and said further radial Soller slit having different opening angles and/or different divergence angles. 17. A diffractometer having a source for generating a primary beam, a sample holder for arranging a sample, a detector for detecting a secondary beam emitted by the sample, and the X-ray optical element of claim 1. 18. The diffractometer of claim 17, wherein the X-ray optical element is installed in the diffractometer in such a fashion that it can be rotated about an axis of rotation which is perpendicular to said axis of said Soller slit. 19. The diffractometer of claim 18, further comprising a motor for rotating the X-ray optical element. 20. The diffractometer of claim 18, further comprising automatic control or computer control of rotation of the X-ray optical element. 21. The diffractometer of claim 17, wherein the X-ray optical element is disposed on a side of the primary beam. 22. The diffractometer of claim 17, wherein the X-ray optical element is disposed on a side of the secondary beam. 23. The diffractometer of claim 22, wherein said detector is disposed in a point of intersection of the lamella directions of at least one radial Soller slit. 24. The diffractometer of claim 21, wherein said sample holder is disposed in a point of intersection of lamella directions of at least one radial Soller slit. 25. The diffractometer of claim 21, wherein said source is disposed in a center of at least one radial Soller slit.