Patent Number: 
Section: claims

1. A limiting device (9) for limiting electromagnetic radiation (3;5;7), which device includes an essentially flat beam cross-section limiter (10) which at least partly encloses at least one passage aperture (l2;13) for beams (5;7), characterized in that the device (9) includes at least a second beam cross-section limiter (14) which, in the active position, constitutes at least one component extending at an angle, which is not zero, to the first beam cross-section limiter (10). 2. A device as claimed in claim 1, characterized in that the second beam cross-section limiter (14) extends perpendicularly to the first beam cross-section limiter (10). 3. A device as claimed in claim 1, characterized in that the first beam cross-section limiter (10) includes two mutually intersecting passage apertures (12;l3) for beams (5;7). 4. A device as claimed in claim 1, characterized in that the second beam cross-section limiter (14) includes a passage aperture (16) for beams (5;7) which commences in an edge zone and is only partly enclosed. 5. A device as claimed in claim 1, characterized in that the passage apertures (12;13;16) of the first and the second beam cross-section limiter (10;14) are formed by respective sectors of a circle. 6. A device as claimed in claim 1, characterized in that the first passage aperture (12) of the first beam cross-section limiter (10) constitutes in projection at least approximately a circle in conjunction with the passage aperture (16) of the second beam cross-section limiter (14). 7. A device as claimed in claim 6, characterized in that the circular contour is such that a beam (5) which enters perpendicularly thereto reaches only edge faces of the first passage aperture (12) of the first beam cross-section limiter (10) as well as the passage aperture (16) of the second beam cross-section limiter (14). 8. A device as claimed in claim 1, characterized in that the second passage aperture (13) of the first beam cross-section limiter (10) constitutes in projection a circle in conjunction with the passage aperture (16) of the second beam cross-section limiter (14). 9. A device as claimed in claim 8, characterized in that the circular contour is such that a beam (7) which is incident on or emanates from this contour at right angles reaches only edge zones of the second passage aperture (13) of the first beam cross-section limiter (10) as well as the passage aperture (16) of the second beam cross-section limiter (14), and that reflected or secondary rays (22) which originate from boundaries of the first passage aperture (12) of the first beam cross-section limiter (10) do not invade the beam (7) emanating from said passage apertures (13;16). 10. A device as claim in claim 1, characterized in that the fist beam cross-section limiter (10) and the second beam cross-section limiter (14) can be detachably connected to one another. 11. An analysis device (A) for the examination of material samples (6) by means of electromagnetic radiation (3; 5; 7), characterized in that the analysis device (A) includes at least one limiting device (9) as claimed in claim 1. 12. An analysis device as claimed in claim 11, characterized in that the limiting device (9) is built into the analysis device (A) in such a manner that a beam (5) which is incident on an optical element, and directed onto a sample (6) passes through the aperture of incidence which is enclosed by the boundaries of the first passage aperture (12) of the first beam cross-section limiter (10) and the boundary of the passage aperture (16) of the second beam cross-section limiter (14) and that a beam (7) which originates from the optical element, traverses the exit aperture which is limited by the boundaries of the second passage aperture (13) of the first beam cross-section limiter (10) and the passage aperture (16) of the second beam cross-section limiter (14). 13. An analysis device as claimed in claim 12, characterized in that the incident beam (5;21) contacts merely edge zones of the first passage aperture (12) of the first beam cross-section limiter (10) and the passage aperture (16) of the second beam cross-section limiter (14). 14. An analysis device as claimed in claim 12, characterized in that secondary rays (22) which are reflected by the first passage aperture of the first beam cross-section limiter (10) or are produced at that area do not traverse the exit aperture formed by the second passage aperture (13) of the first beam cross-section limiter (10) and the passage aperture (16) of the second beam cross-section limiter (14). 15. An analysis device as claimed in claim 11, characterized in that the first passage aperture (12) and the second passage aperture (13) of the first beam cross-section limiter (10) are of different size. 16. A limiting device (9) for limiting electromagnetic radiation (3;5;7), which device includes an essentially flat beam cross-section limiter (10) which at least partly encloses two mutually intersecting passage apertures (12;13) for beams (5;7), characterized in that the device (9) includes a second beam cross-section limiter (14) which includes a passage aperture (16) far beams (5;7) which commences in an edge zone and is only partly enclosed.