Electron microscopy
These images show a transmission electron microscope (TEM) along with a schematic of its inner components. The optics of a TEM are analogous to those of a compound light microscope except that the illumination is provided by a beam of electrons which are focused by electromagnetic, rather than glass, lenses. The images produced result from the interaction of the electrons with the heavy metals as they passes through the tissue section. This type of electron microscope is referred to as a transmission electron microscopy because electrons pass through the specimen.
Column >
The components of the electron microscope are enclosed in a metal column that is kept under high vacuum to permit the flow of electrons inside the column.
Electron source
Electrons are emitted from a wire filament located at the top of the column.
- Electron beam
Electrons are emitted from a wire filament located at the top of the column.
Sample entry port >
Sections on grids are introduced to the column just above the objective lens.
- Grid with sections
Sections on grids are introduced to the column just above the objective lens.
Lenses >
The electron microscope uses a set of cylindrical, electromagnetic lenses that are arranged in an analogous fashion to the glass lenses of the light microscope.
- Condenser lens >
The condenser lens focuses the electrons into a beam after they are emitted from the filament.
- Objective lens >
The beam passes through the specimen and then into the objective lens. The objective lens magnifies and forms an intermediate image of the tissue.
- Projector lens >
The projector lens adds additional magnification and projects the final image onto a phosphorescent screen for viewing. The projector lens is analogous to the eyepiece in a light microscope.
Viewing screen >
A viewable image is produced on a phosphorescent screen. The final image is viewed on the screen with binocular viewer. Images are permanently captured either digitally or on photographic film.
- Binocular viewer
A viewable image is produced on a phosphorescent screen. The final image is viewed on the screen with binocular viewer. Images are permanently captured either digitally or on photographic film.
Image source >
Modified from Adam Blatner, MD, Further Developments in Microscopy, https://www.blatner.com/adam/consctransf/historyofmedicine/1-overview/modernmicro.html
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