The TEM and Its Optics
This chapter is an introduction to the transmission electron microscope (TEM), using ray diagrams to discuss its essential optical design and its component subsystems. Bright- and dark-field imaging are explained, as is selected area diffraction, convergent beam diffraction, high-angle annular dark field imaging, and high-resolution transmission electron microscopy. Some practical issues of spectroscopy, diffraction, and imaging are discussed. Both glass lenses and magnetic lenses are described, and their focusing action is explained by ray tracing and by phase distortions of the wavefront. Brightness and other issues underlying image resolution are described, and limits of resolution are presented for different high-resolution methods.