Practical Electron Microscopy and Database

An Online Book, Second Edition by Dr. Yougui Liao (2006)

Practical Electron Microscopy and Database - An Online Book

Chapter/Index: Introduction | A | B | C | D | E | F | G | H | I | J | K | L | M | N | O | P | Q | R | S | T | U | V | W | X | Y | Z | Appendix

Focusing Properties of Electromagnetic Lenses Affected by Aberrations

The primary quality of electron optical elements (electromagnetic lenses) in electron microscopes (EMs) is usually degraded by secondary effects. They are aberrations, which can be categorized by three groups: geometric, chromatic, and parasitic aberrations, such as spherical aberration, diffraction aberration, astigmatism, coma aberration, chromatic aberration, and higher-order aberrations. All such defects will perturb the focusing properties of the corresponding lenses.