THE RELATIVE PRECISION OF CRYSTAL ORIENTATIONS MEASURED FROM ELECTRONBACKSCATTERING PATTERNS

Recently developed statistical methods for analysing orientation data are presented and applied here in a study of the precision by which cr ystal orientations can be measured from electron backscattering patter ns. The use of these methods allows a direct comparison to be made bet ween the precision obtained with manually and automatically localized bands, which is important owing to a more and more widespread use of f ully automatic analysis of electron backscattering patterns. Curves wh ich show how the precision depends on the pattern quality and on the n umber of bands used for the orientation measurements are presented for both manually and automatically localized bands. Typical values for t he relative precision of crystal orientations measured from electron b ackscattering patterns are shown to be of the order of 0.5 degrees for manually localized bands and 0.75 degrees for automatically localized bands, when about 10 bands are used for the measurements, In a more r ealistic situation where a careful operator is willing to localize fou r to five bands in each pattern, the precision of the measured crystal orientations is similar to that obtained for automatically localized bands.