Scanning electron microscope

A scanning electron microscope scans a focused electron beam across a specimen and forms images from signals emitted at or near its surface.

Electron beam: A stream of electrons moving in a controlled direction, often shaped and focused by electromagnetic fields. The instrument raster-scans this focused stream across the specimen.
Electromagnetic lens: A coil-and-pole-piece assembly that focuses or steers charged particles using a magnetic field. Electromagnetic lenses focus the electron probe and control its path.
Energy-dispersive X-ray spectroscopy: An analytical method that identifies elements by measuring the energies of characteristic X-rays emitted by a sample. Paired with an SEM, it maps elemental composition alongside surface images.
Transmission electron microscope: An electron microscope that forms images from electrons transmitted through a thin specimen. TEM emphasizes internal structure through thin samples, unlike SEM's surface-derived signals.
Manfred von Ardenne: A German physicist and engineer who developed an early scanning electron microscope in the 1930s. His early instrument established the scanning-beam approach to electron microscopy.
Secondary electron: A low-energy electron ejected from a specimen after energy transfer from an incident particle. Secondary-electron yield reveals fine surface topography.
Electron gun: A source that emits electrons and accelerates them into a beam. It supplies the electrons that the microscope focuses onto the specimen.
Electron backscatter diffraction: A crystallographic technique that analyzes diffraction patterns from electrons backscattered by a tilted specimen. SEM-based EBSD maps crystal orientations and grain boundaries.
Optical microscope: A microscope that uses visible light and optical lenses to magnify specimens. Visible-light imaging is simpler but has lower resolution than electron-beam imaging.
Charles Oatley: A British engineer whose Cambridge group advanced practical scanning electron microscopy after World War II. His research group helped turn SEM into a reliable instrument.

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