Abstract: A charged particle energy analyzer (10) includes inner and outer cylindrically symmetric electrodes (11,12) arranged coaxially on a longitudinal axis (z-z) of the analyzer. A position-sensitive detector (17) has a particle-receiving detection surface located off-axis, at a radial spacing from the longitudinal axis (z-z) less than the radius of the inner electrode (11). Methods of operating the charged particle energy analyzer in first and second order focussing modes are described. A position-sensitive detector (17) suitable for use in “parallel analyzers” is described (FIGS. 7 and 8).

Abstract: A charged particle energy analyser (10) includes inner and outer cylindrically symmetric electrodes (11,12) arranged coaxially on a longitudinal axis (z-z) of the analyser. A position-sensitive detector (17) has a particle-receiving detection surface located off-axis, at a radial spacing from the longitudinal axis (z-z) less than the radius of the inner electrode (11). Methods of operating the charged particle energy analyser in first and second order focussing modes are described. A position-sensitive detector (17) suitable for use in “parallel analysers” is described (FIGS. 7 and 8).

Abstract: Charged particle energy analysers enabling simultaneous high transmission and energy resolution are described. The analysers have an electrode structure (11) comprising coaxial inner and outer electrodes (14, 15) having inner and outer electrode surfaces (IS, OS) respectively. The inner and outer electrode surfaces are defined, at least in part, by spheroidal surfaces having meridonal planes of symmetry orthogonal to a longitudinal axis of the electrode structure (11). The inner and outer electrode surfaces are generated by rotation, about the longitudinal axis, of arcs of two non-concentric circles having different radii R2 and R1 respectively, R2 being greater than R1. The distance of the outer electrode surface from the longitudinal axis in the respective meridonal plane is R01 and the distance of the inner electrode surface from the longitudinal axis in the respective plane is R02 and R1, R2, R01 and R02 have a defined relationship.

Abstract: Charged particle energy analysers enabling simultaneous high transmission and energy resolution are described. The analysers have an electrode structure (11) comprising coaxial inner and outer electrodes (14, 15) having inner and outer electrode surfaces (IS, OS) respectively. The inner and outer electrode surfaces are defined, at least in part, by spheroidal surfaces having meridonal planes of symmetry orthogonal to a longitudinal axis of the electrode structure (11). The inner and outer electrode surfaces are generated by rotation, about the longitudinal axis, of arcs of two non-concentric circles having different radii R2 and R1 respectively, R2 being greater than R1. The distance of the outer electrode surface from the longitudinal axis in the respective meridonal plane is R01 and the distance of the inner electrode surface from the longitudinal axis in the respective plane is R02 and R1, R2, R01 and R02 have a defined relationship.

Abstract: A particle optical apparatus including an aperture plate for shaping a particle beam before the particle beam enters a monochromator filter assembly. The aperture plate has at least one aperture and is adjustable with respect to the monochromator filter assembly, in normal operating conditions, so that the size of the aperture used to shape the particle beam can be varied, and therefore the beam current entering the filter assembly can be varied.