High resolution transmission electron microscopy (HRTEM) is identical to transmission electron microscopy (TEM) imaging except that the magnifications used are high enough to easily see the lattice spacing of inorganic materials (typically on the order of several Å). Although such lattice spacings can easily be recorded onto film at moderate magnifications (the 3.4 Å spacing between graphite layers can be recorded onto film at magnifications as low as 15,000-20,000x), CCD cameras and much higher magnifications (usually above 200,000 or 300,000x at the plane of the imaging device) allow the user to control the defocus much more easily and produce the best HRTEM images. Visualization of these atomic spacings requires a more stable goniometer, a brighter electron source and more stable electronics than are found in most electron microscopes not designed for HRTEM. Virtually all recently built intermediate voltage instruments (i.e., electron microscopes operating at 200, 300 and 400 kV) meet the necessary requirements for HRTEM, and it is more often specimen and environmental issues that prevent such instruments from recording images with atomic resolution information.
