ABSTRACT
This chapter describes the features of a field emission gun-scanning transmission electron microscopy (STEM) instrument. It describes the electron optics in terminology specific to the STEM mode of operation. A dedicated STEM is more closely related to an SEM than a TEM in its optical design, so it might be described as an SEM with a transmission attachment or a S(T)EM. The chapter discusses the optical components that are found closest to the specimen itself (including the specimen holder). The text is by necessity becoming more specific to one type of instrument and most of the differences between instruments are to be found in the details of this region. Electron optical design improvements combined with streamlined analysis facilities have proved effective in solving many challenging materials science problems, while the limits of resolution and information are being established as attainable goals.
