Orientation Imaging Microscopy in the TEM

Abstract

Abstract There is a range of techniques now available for the study of crystallographic orientation in materials. Among these, Orientation Imaging Microscopy (OIM) for the SEM is being increasingly applied. This technique is, however, limited by the spatial resolution of the SEM (∼0.5 μm). TEM orientation measurements and imaging provides the necessary alternative to SEM measurements due to the much higher spatial resolution of the TEM (∼10 μm). In TEM crystal orientation measurements Kikuchi patterns are preferred over selected area spot patterns due to higher accuracy and spatial resolution. The earliest means of automation of TEM orientation measurements involved the use of digital scanners and beam deflection measurment for computerized semi-automatic indexing of the patterns. In recent years fully automatic on-line orientation determination has been developed. This has come about as a result of the advances in image processing for automatic indexing of backscatter Kikuchi patterns in the SEM, and the emergence of slow-scan CCD cameras with a large dynamic range.