Chapter Four: Quadrupole systems: Their suitability for specific tasks
Peter Hawkes
Abstract
Quadrupole lenses could be used in aberration correctors, as objective lenses at very high voltages, as projector or probe-forming lenses or to form line images. These possibilities are surveyed critically.
Keywords
Quadrupole multiplets; Geometrical aberration correction; Quadrupoles as lenses; Line images; Isolated octopoles; Chromatic aberration correction
The number of reasons for introducing quadrupoles and octopoles into practical systems is limited and it is difficult to foresee any but the following roles for these elements:
- (i) As corrector units, to reduce the spherical and chromatic aberrations of good round lenses (Archard–Deltrap correctors). ...
