## Structure The typical structure of TEM is similar to the optical ones--it is a column and electron beam travels inside. However, unlike the light microscope with the bottom-top structure, TEM is top-bottom. Electrons travels from the top, passing through several electromagnetic lens, and finally project to the fluorescent screen, or cameras. From top to bottom, we have: - [[Electron guns|electron guns]] - filament - Wehnelt - [[Condenser lens|condenser lens]] - CL 1 - CL 2 - CL aperture - [[Specimen holder|sample holder]] - [[Objective and intermediate lens|objective & intermediate lens]] - objective lens - objective lens aperture - selected area aperture - intermediate lens - projector lens, fluorescent screen, camera Some system may have additional equipment like aberration corrector or extra apertures, providing further controls on electron beams. But what listed above is the most common setup. ![[Drawing 2023-09-30 00.08.11.excalidraw.svg]]