A Cost-Effective Method for Minimizing the Sphere-of-Confusion Error of X-Ray Microdiffractometers

Microdiffractometers are used to obtain x-ray diffraction data from regions that are tens of microns or less in size. If a microdiffractometer's rotation circles do not share the same center, or if the feature-of-interest on a sample does not lie at the center of all rotations, the sample feature will, upon rotation of the diffractometer circles, precess through a finite volume known as the sphere-of-confusion (SoC). If the size of the beam used for diffraction analysis is smaller than the SoC diameter, the beam may actually move off the region-of-interest. In this article, we describe a new technique, based on x-ray fluorescence imaging and coordinate transforms, which can maintain the sample position to within ± 6 µm over all rotations even when a commercial diffractometer is used as the base for the microdiffracometer system.