This book discusses the geometrical aberrations of lenses; spherical aberration of electric and magnetic lenses; and measurement of the spherical aberration of various electric and magnetic lenses. The theory of diffraction; influence of space charge in high density electron beams; and chromatic aberration are also deliberated.

This publication likewise covers the classification of the geometrical aberrations; derivation of the coefficient of spherical aberration according to Glaser; and pepper-pot method or Hartmann's test. The Fraunhofers diffraction through a circular aperture; force due to coulomb repulsion; and upper limit of the chromatic aberration of magnetic lenses are also included.

This volume is valuable to industrial scientists and engineers concerned with electrostatic and magnetic lenses.

Contenu

List of Symbols
IX. Geometrical Aberrations of Lenses
9.1 Types of Aberrations
9.2 Third-Order Theory
9.3 Geometrical Aberrations
9.4 Classification of the Geometrical Aberrations
9.5 Description of the Aberration Figures
9.6 Calculation of the Geometrical Aberration Coefficients
9.7 Solution for Paraxial Rays
9.8 Calculation of the Aberrations
9.9 Spherical Aberration
9.10 Coma Coefficient
9.11 Anisotropie Coma Coefficient
9.12 Curvature Coefficient
9.13 Astigmatism Coefficient
9.14 Anisotropie Astigmatism Coefficient
9.15 Distortion Coefficient
9.16 Anisotropie Distortion Coefficient
Further Reading
X. The Spherical Aberration of Electric and Magnetic Lenses
10.1 The Impossibility of Canceling the Spherical Aberration
10.2 Definition of the Coefficient Cs
10.3 Disk of Minimum Confusion
10.4 The Spherical Aberration of the Combination of Two Thin Lenses
10.5 Conversion of Cs from One Object Position to Another
10.6 Derivation of the Coefficient of Spherical Aberration according to Glaser
10.7 Glaser's Expression for Cs of Purely Magnetic Fields
10.8 Spherical Aberration of a Magnetic Lens with a Bell-Shaped Field Distribution
10.9 Spherical Aberration of the Symmetrical Magnetic Lens
10.10 Spherical Aberration of an Electrostatic Immersion Lens
10.11 Spherical Aberration of Einzel Lenses
Further Reading
XI. Measurement of the Spherical Aberration of Various Electric and Magnetic Lenses
11.1 The Pepperpot Method or Hartmann's Test
11.2 The Shadow Method
11.3 The Halo Method
11.4 The Knife-Edge Method
11.5 The Tilt Method
11.6 The Diffraction Method
11.7 The Combined Tilt and Diffraction Method
Further Reading
XII. Theory of Diffraction
12.1 General Properties of a Wave
12.2 The Plane Wave
12.3 The de Broglie and Planck Relations
12.4 Huygens' Principle
12.5 Diffraction
12.6 The Wave Equation
12.7 Kirchhoff's Diffraction Equation
12.8 Fraunhofers Diffraction through a Circular Aperture
12.9 Resolving Power of an Ideal Optical System
XIII. The Influence of Space Charge in High Density Electron Beams
13.1 Force Due to Magnetic Attraction
13.2 Force Due to Coulomb Repulsion
13.3 The Universal Curve
13.4 Numerical Examples
Further Reading
XIV. Chromatic Aberration
14.1 Development of the Expressions for Chromatic Aberration
14.2 Chromatic Aberration at the Focal Point
14.3 Upper Limit of the Chromatic Aberration of Magnetic Lenses
14.4 Upper Limit of the Chromatic Aberration of Electrostatic Lenses
14.5 Coefficient of Chromatic Aberration
14.6 Chromatic Aberration of a Magnetic Lens with the Glaser Bell-Shaped Field
14.7 Minimum Value of Cc and 8
14.8 Chromatic Aberration of the Symmetrical Magnetic Lens
14.9 Current Limit at the Focus Due to the Velocity Spread of the Emitted Electrons
14.10 Numerical Example
14.11 Simplified Derivation
Further Reading
References
Index