| 摘要 |
An X-ray diffractometer (1; 24; 30) has a mechanism without toothed ring and is suited to move the two legs of a goniometer, on which the source (2) and detector (3; 31) are respectively disposed, at the same time and in a correlated fashion, wherein the Theta-angle can be scanned, and at the same time a Theta-Theta-geometry (Bragg-Brentano measurement geometry) is always maintained. This is achieved in that each goniometer leg (or linkage (5, 6; 25, 26)) has a common main center of rotation HDP and also one respective auxiliary center of rotation HD1, HD2. The two auxiliary centers of rotation are symmetrically disposed with respect to a symmetry plane E which contains the main center of rotation, and can be moved on a guidance (13; 13a, 13b) that is symmetrical with respect to the plane E. The main center of rotation can only be moved in the plane E, e.g. along a rail guidance. When the main center of rotation, where the sample to be measured is arranged, is moved in the plane E, the guidance and the goniometer legs cause an opposite angular shift of the goniometer legs, such that the Theta-Theta-geometry with respect to the source and the detector is maintained. The movement of the main center of rotation relative to the guidance can be easily driven by means of one single motor (22).
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