Convenient off-line error quantification and characterization of concentricity of two circles of rotation for diffractometer alignment

Abstract

To ensure concentricity of the θ–2θ rotation stages, but with a very limited 2θ range of rotation, an alignment technique using two dial gauges mounted at right angles to each other (XandYaxes) is described. The deflections of the orthogonal dial gauges are measured as a function of 2θ, with their probes impinging on a cylindrical pin centred on the θ axis. TheXandYcorrections required to bring the two rotation stages into concentricity can then be found using a least-squares fittingviaa freestanding program orviathe `solver' optimization within the MicrosoftExcelspreadsheet software. The same dial gauges provide guidance for applying the required positional corrections. AnExcelspreadsheet for determining theXandYcorrectionsvialeast squares has been deposited.