ABSTRACT
Electron microscopy is a powerful tool that allows materials scientists to analyze the microstructure, chemistry and crystal structure of materials from areas smaller than 1 m. In general, electron microscopy is divided into two different areas; surface scanning electron microscopy (1) and transmission electron microscopy (2). The fundamental difference between these two classes of instrument is that an image from a scanning electron beam instrument is built up by scanning a focused, highly convergent electron probe (many times smaller than the area being imaged) over an area of the sample and measuring a signal produced from the interaction of the electron beam with the specimen, whereas a transmission electron microscope (TEM) utilizes a parallel (coherent) stationary beam of electrons illuminating an area of the sample and forming an image using some portion of the electrons which pass through the specimen. In this regard, images from scanning electron beam instruments are sometimes referred to as virtual images because the image is comprised of a signal different than that of the incident electron beam, whereas the image from a transmission electron microscope can be classified as a real image.
