Transmission Electron Microscopy (TEM) is a powerful imaging technique that uses a high-energy electron beam transmitted through an ultra-thin specimen to generate highly detailed images at the nanometer scale. Unlike light microscopes, TEM can resolve fine structural details inside cells, viruses, and materials, revealing internal morphology, crystallographic information, and even atomic arrangements. In TEM, electrons interact with the sample as they pass through, and the resulting transmitted electrons are focused by electromagnetic lenses to form an image on a screen or digital detector. This method is widely used in materials science, nanotechnology, and biology for ultrastructural analysis and characterization.

1. FS 107 Fundamentals of Microbiology
Transmission Electron Microscope
J. Bovas Joel

2. Principle
• Transmission Electron Microscopy (TEM)
uses a focused beam of high-energy
electrons to probe an ultra-thin specimen,
typically less than 100 nm thick.
• As the electron beam interacts with the
sample, it undergoes transmission,
scattering, or absorption.
• The transmitted electrons, which carry
information about the internal structure,
form an image when focused by lenses and
detected.

3. Parts
1. Electron Gun: Produces the electron beam
2. Condenser Lenses: Focus the electron beam onto
the sample.
3. Specimen Stage: Holds the thin sample in place.
4. Objective Lens: Magnifies the transmitted
electrons.
5. Intermediate & Projector Lenses: Further magnify
the image.
6. Detectors: Capture the final image.
7. Vacuum System: Prevents scattering of electrons by
air.

4. Construction
• The electron gun emits high-energy electrons
directed toward the condenser lens to form a
focused beam.
• The specimen stage holds the specimen,
which is typically very thin and mounted on a
support grid.
• The beam passes through the specimen, and
transmitted electrons are focused by the
objective lens to form a magnified image.
• Intermediate and projector lenses further
magnify the image before it is projected onto
a fluorescent screen or captured by a
camera.

5. Success consists of going from failure
to failure without loss of enthusiasm