How do Electron Microscopes work?
Electron Microscopes (EMs) function exactly as their optical counterparts except that they use a focused beam of electrons instead of light to "image" the specimen and gain information about its structure and composition.
The basic steps involved in all EMs are:
- A stream of electrons is formed and accelerated toward the specimen using a positive electrical potential
- This stream is confined and focused using metal apertures and magnetic lenses into a thin, monochromatic beam
- This beam is projected onto the sample using a magnetic lens
- Interactions occur inside the irradiated sample, affecting the electron beam
- These interactions and effects are detected and transformed into an image