ADVANCES IN AUTOMATIC EBSP SINGLE ORIENTATION MEASUREMENTS

A completely automated system which couples automatic analysis of elec tron backscatter diffraction patterns (EBSPs) with precise movement of the sample in the SEM is described. The Hough transform is implemente d into an existing technique for identifying lattice orientation throu gh automatic analysis of EBSPs. The ability of the Hough transform app roach to correctly identify diffraction bands is quantitatively compar ed with the Burns algorithm. Both methods were tested on 1000 EBSPs fr om well annealed oxygen-free, electrical grade (OFE) copper, 120 patte rns 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-c ast Al) and 81-85% (deformed Al) correctly determined orientations (le ss 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 satisfie s the detected bands most completely, a method of averaging solutions obtained from different triplets of bands is introduced.