Principles of Electron Optics

Transcription

1 Principles of Electron Optics Volume 2 Applied Geometrical Optics by P. W. HAWKES CNRS Laboratory of Electron Optics, Toulouse, France and E. KASPER Institut für Angewandte Physik Universität Tübingen, Federal Republic of Germany ACADEMIC PRESS Harcourt Brace lovanovich, Publishers London San Diego New York Berkeley Boston Sydney Tokyo Toronto

2 of Volume 2 Applied Geometrical Optics Preface PART VII - INSTRUMENTAL OPTICS Electrostatic Lenses Immersion lenses Einzel lenses Grid or foil lenses Cylindrical lenses Magnetic Lenses Field models Measurements and universal curves Ultimate lens performance Lenses of unusual geometry Special purpose lenses Electron Mirrors The electron mirror microscope Mirrors in energy analysis Cathode Lenses and Field-Emission Microscopy Cathode lenses Field emission microscopy Quadrupole Lenses The rectangular and bell-shaped models Isolated quadrupoles and doublets Triplets Quadruplets Other quadrupole geometries Deflection Systems

3 VI 40.2 Field models for magnetic deflection systems The variable-axis lens Alternative concepts Deflection modes and beam-shaping techniques 848 PART VIII - ABERRATION CORRECTION AND BEAM INTENSITY DISTRIBUTION (CAUSTICS) 41 Aberration Correction Multipole correctors Foil lenses and space charge Axial conductors and mirrors High-frequency lenses Other aspects of aberration correction Caustics and their Applications The concept of the caustic The caustic of a round lens The caustic of an astigmatic lens Intensity considerations Higher order focusing properties Applications of annular systems 897 PART IX - ELECTRON GUNS 43 General Features of Electron Guns Thermionic electron guns Field electron emission guns Beam transport systems Theory of Electron Emission General relations Transmission through a plane barrier Thermionic electron emission The tunnel effect Field electron emission Extended Schottky emission Concluding remarks 933

4 Pointed Cathodes without Space Charge The spherical cathode The diode approximation Field calculation in electron sources with pointed cathodes Simple models Space Charge Effects The spherical diode Asymptotic properties and generalizations Determination of the space charge Brightness Application of Liouville's theorem The maximum brightness The influence of apertures Lenz's brightness theory Measurement of the brightness Emittance Trace space and hyperemittance Two-dimensional emittances Brightness and emittance Emittance diagrams The Boersch Effect The shift of the mean energy Thermodynamic considerations Analytical calculations Complete Electron Guns The justification of the point source model The lens system in field emission devices Hybrid emission Conventional thermionic guns Pierce guns Further reading vii PART X - SYSTEMS WITH A CURVED OPTIC AXIS 51 General Curvilinear Systems of a curvilinear coordinate system Series expansion of the potentials and fields 1042

5 VIII Variational principle and trajectory equations Simplifying symmetries Trajectory equations for symmetric configurations Aberration theory Magnetic Sector Fields Devices with a circular optic axis Radial (horizontal) focusing for the model field (52.2) The linear dispersion The axial (vertical) focusing Fringing field effects Aberration theory: the homogeneous field (n = o) Optimization procedures Unified Theories of Ion Optical Systems Electrostatic prisms A unified version of the theory The literature of ion optics Notes and References Part VII, s Part VIII, s 41 and 42 Part IX, s PartX, s Confe rence Proceedings Index