A new method to position a sample on a rotating axis accurately

An important point for the quality of all diffraction measurements is the adjustment and alignment of the diffractometer. For the example of an X-ray diffractometer for position-sensitive stress measurements, a simple and precise optical method of positioning the sample relative to the rotation axes is presented. The adjustment procedure is discussed and analysed in general for all diffractometers with attention being paid to the necessary translations and rotations. The principle, applied here, is the elimination of the relative motion of a reference mark on the sample surface, on rotation. This method can be applied to all problems in which a point on the surface of a body has to be brought into a definite position relative to a rotating axis. The adjustment procedure is carried out on the sample to be measured.