An electrostatic deflector for energy selection of a beam of charged particles has a plurality of main deflector plates arrayed in a generally cylindrical basic shape and to which electrostatic potentials are applied. The main deflector plates are shaped and the potentials are applied to generate a path of said beam from an input side of said deflector to an output side thereof by virtue of a deflecting field which is increasingly weakened to both sides of a central portion of the beam toward the main deflector plates relative to a field of ideal cylindrical shape, thereby causing second order angular aberration of the beam to substantially vanish. A pair of end deflector plates at opposite ends of the cylindrical basic shape have a repulsive potential with respect to the beam to effect focussing of the beam perpendicular to a dispersion plane of the deflector.

Angular electrostatic filters and methods of filtering that remove energy contaminants from a ribbon shaped ion beam are disclosed. An angular electrostatic filter comprises a top deflection plate and a bottom deflection plate extending from an entrance side to an exit side of the filter. The bottom deflection plate is substantially parallel to the top deflection plate and includes an angle portion. An entrance focus electrode is positioned on the entrance side of the filter and an exit focus electrode is positioned on the exit side of the filter and both serve to focus the ion beam. Edge electrodes are positioned between the top and bottom deflection plates and at sides of the filter to mitigate edge effects. A negative bias is also applied to the top and bottom plates to mitigate space charge by elevating the beam energy.

A charged particle energy analyzer includes two hemispherical electrodes and means for developing an inverse square electric field in the gap between the two electrodes. An afocal charged particle lens arrangement is arranged to project a charged particle image of a sample into the electric field. Two baffles are disposed in the gap between the electrodes the baffles being effective to restrict the energy and angular divergence of the particles transmitted by the analyzer, the baffles being positioned so as to reduce the dependence of the energy and the orientation of the charged particles transmitted by the baffles on the position of the particles within the image. A two-dimensional detector is arranged to detect the charged particle image transmitted by the analyzer.

A Wien filter is used with secondary electrons that are emitted from a primary electron beam scanning a sample surface in a scanning electron microscope (SEM) used as an energy analyzer or a spin rotater with charged particle beams. The beam is focussed into an interior area of the filter that has magnetic and electric fields generated to cross one another. The beam intersects the crossed fields perpendicularly. The faces of either the magnetic pole pieces or the electrodes have a shape approximating the shape of a portion of a hyperbola, while the other of the faces are substantially planar. Auxiliary electrodes extend parallel to the beam's path of travel between the electrodes. The filter provides a wide area that enables stigmatic focussing of a wide diameter beam.

An electron energy spectrometer having an electron energy analyzer equipped with plural detectors including a reference detector. The energy of electrons impinging on the reference detector is stepped in increments. The value of these increments can be set at will. The spectrometer has improved detection accuracy and improved detection sensitivity. The spectrometer irradiates the surface of a sample with an electron beam. The energy of the electron beam is swept. The intensities of electrons ejected from the sample surface are analyzed. This instrument utilizes the multidetector scheme. Data about the intensities of the electrons is collected. Interpolation calculations are performed at each value of the energy according to the collected data.