ADVANCES IN AUTOMATIC EBSP SINGLE ORIENTATION MEASUREMENTS

A completely automated system which couples automatic analysis of electron backscatter diffraction patterns (EBSPs) with precise movement of the sample in the SEM is described. The Hough transform is implemented into an existing technique for identifying lattice orientation through automatic analysis of EBSPs. The ability of the Hough transform approach to correctly identify diffraction bands is quantitatively compared with the Burns algorithm. Both methods were tested on 1000 EBSPs from well annealed oxygen-free, electrical grade (OFE) copper, 120 patterns from as-cast commercially pure aluminum and 106 patterns from 40% channel-die compressed aluminum. Only slight differences were found in the ability of the methods to correctly identify bands in the sample EBSPs. The three test runs resulted in 95-99% (OFE Cu), 97.5-99% (as-cast Al) and 81-85% (deformed Al) correctly determined orientations (less than 5-degrees off the manually determined reference orientations). The limits in the ability of the band detection algorithms to fix the bands exactly are discussed. To obtain the orientation which satisfies the detected bands most completely, a method of averaging solutions obtained from different triplets of bands is introduced.