Accurate characterization of electron diffraction patterns can be tedious, which encourages development of computer assisted tools and methods. We developed a spot measurement tool to characterize rapidly arrays of diffraction spots that are characteristic of a single crystal, and to measure precisely the d-spacing values for individual spots. The spot tool determines these vectors for averaged measurements from many spots in a digital image of the diffraction pattern. Previously we developed automated methods for spot pattern analysis. Why make an operator-assisted tool? This tool is faster than either our automated or entirely manual methods, and it allows assessment of the quality of the data at the beginning of the analysis.
It is easy to see regular patterns of spots in a zone axis diffraction pattern (Fig. 1.1). An operator guides the initial calculations by adjusting an array of circles to approximately cover the spots in the pattern to be analyzed.