Effect of Defocusing on Black-and-White Contrast of Small Defects

Abstract

Computer modelling is used to study the specific features of defocused electron microscopy images of small dislocation loops and coherent precipitates. Defocusing of the objective lens is shown to result in variations of black‐and‐white contrast and size which is dependent on the defect location depth and excitation error. Methods are proposed of determining the type (interstitial or vacancy) of inclined dislocation loops using microphotographs.