Sphere of confusion of a goniometer: measurements, techniques and results

In the diffraction community, the goniometer is the main part of the diffractometer, essential for orienting the samples. To characterize the goniometer, the sphere of confusion (SoC) has been measured. The SoC describes the minimal sphere that enclosed the measurements. This essential information is very important for the diffractometer users. In collaboration with Symetrie Inc., Soleil Synchrotron and the CEA, the SoC has been measured with three different metrology methods. These three measurement techniques and the associated results are discussed in this article.