Patent Number: 
Section: claims

1. An X-ray analysis instrument or an X-ray diffractometer, comprising:an X-ray source that emits an X-ray beam;an X-ray optics or a multi-layer X-ray mirror;a collimator mechanism, said collimator mechanism defining an aperture window having an aperture opening through which at least part of the X-ray beam passes, said aperture opening being at least as large as a cross-section of the X-ray beam at a location of said aperture window; andmeans for gradual movement of the aperture window in at least one direction transversely to the X-ray beam, wherein a path of movement of said aperture window by said gradual movement means in said at least one direction is at least twice as large as an extension of the X-ray beam in that direction at said location of said aperture window. 2. The X-ray analysis instrument of claim 1, wherein the collimator mechanism comprises means for gradual movement of the aperture window in two independent directions transversely to the X-ray beam, a respective path of movement of said aperture window which is accessible by said collimator mechanism in each of said independent directions being at least twice as large as an extension of the X-ray beam at said location of the aperture window in a respective said independent direction. 3. The X-ray analysis instrument of claim 1, wherein a size of said aperture opening cannot be adjusted. 4. The X-ray analysis instrument of claim 1, wherein a size of said aperture opening can be adjusted by means of said collimator mechanism, wherein said aperture opening can be adjusted to a size which is at least as large as said cross-section of the X-ray beam at said location of said aperture window. 5. The X-ray analysis instrument of claim 4, wherein said collimator mechanism for adjusting said size of said aperture opening has two L-shaped aperture sections that can be moved with respect to one another. 6. The X-ray analysis instrument of claim 1, wherein said collimator mechanism is disposed on an output side of said X-ray optics. 7. The X-ray analysis instrument of claim 1, wherein said aperture window has a square aperture opening, the X-ray beam having an approximately square cross-section at said location of said aperture window, wherein side edges of said square aperture opening and said square cross-section of the X-ray beam are oriented parallel to each other and said at least one direction in which said aperture window can be moved is oriented along a diagonal of said square aperture opening. 8. The X-ray analysis instrument of claim 1, wherein said X-ray optics is disposed in a gas-tight optical housing and said collimator mechanism is disposed in a gas-tight collimator housing, wherein said optical housing and said collimator housing are evacuated or flooded with a protective gas. 9. The X-ray analysis instrument of claim 1, wherein said X-ray optics and said collimator mechanism are disposed in a common gas-tight housing, wherein said common housing is evacuated or flooded with a protective gas. 10. The X-ray analysis instrument of claim 1, wherein said means for gradual movement of said aperture window comprise at least one micrometer screw and/or at least one fine thread bolt. 11. The X-ray analysis instrument of claim 1, wherein said collimator mechanism has a holder for an exchangeable aperture window element and said holder can be moved by said means for gradual movement of the aperture window. 12. A method for operating the X-ray analysis instrument of claim 1, wherein the X-ray beam is emitted by the X-ray source to be imaged on a sample through the X-ray optics, the method comprising the step of:selecting a portion of the X-ray beam on the X-ray optics that is remote from the source for adjusting or reducing a focus size of the X-ray beam at the location of the sample by means of the aperture opening of the aperture window. 13. The method of claim 12, wherein the focus size of the X-ray beam at the location of the sample is adjusted to a size of the sample. 14. The method of claim 12, wherein the selected portion of the X-ray beam remote from the source has a below-average mean photon flux density compared to a remaining portion of the X-ray beam. 15. The method of claim 12, wherein the aperture window is positioned in such a fashion that X-ray radiation does not pass through a part of the aperture opening of the aperture window. 16. The method of claim 12, wherein the aperture window is disposed in the X-ray beam between the X-ray optics and the sample.