Positioning errors during stepped scans in X-ray crystallography

It is demonstrated that many X-ray measurements, especially at grazing incidence, allow continuous data acquisition during stepped scans without deadtime for diffractometer motor motions. Analyzing the deviation from the ideal trajectory during independent motor movements, it is found that the deviation from the direct line connecting two data points in reciprocal space is very small for large volumes of reciprocal space. A synchronization algorithm to determine coordinated motor movements that follow the direct line connecting the data points is presented. Verification experiments on a six-circle diffractometer demonstrate the validity of the approach.