Abstract: In an electron beam device such as a raster electron microscope, two annular detectors are arranged at a distinct distance along the optical axis between a beam producer and an objective. The distance between the two detectors amounts to at least 25% of the distance between the specimen-side detector and the specimen. The source-side detector serves for detection of back-scattered or secondary electrons which are transmitted through the bore provided through the specimen-side detector for the passage of the primary particle beam. The source-side detector is a conversion diaphragm with an Everhart Thornley detector arranged laterally thereof. The conversion diaphragm produces secondary electrons on impingement of charged particles. By application of two detectors offset in the direction of the optical axis, the yield of the secondary electrons used for image production is increased. The secondary electrons are separated according to their angle of emergence from the specimen.

Abstract: The invention is directed to an electron microscope having a magnetic energy filter. The energy filter has four deflection regions and seven hexapole correctors for correcting the aberrations of the energy filter. A projection system is mounted downstream of the filter. With the projection system, the achromatic image plane is selectively imaged onto the CCD camera for energy-filtered object imaging or the dispersion plane is imaged on a CCD camera for spectrum detection. For an object registration, the hexapoles are so excited that all geometric aberrations of the second order are corrected in the achromatic image plane and in the dispersion plane. For the spectrum imaging, the excitation of three hexapoles is so changed that the axial chromatic aberration of the filter is corrected while maintaining the correction of the spherical aberration in the achromatic image plane and while maintaining the correction of all geometric errors of the second order in the dispersion plane.

Abstract: A particle beam apparatus that can be used, in particular in an electron microscope, has a dispersively imaging energy filter in the illumination beam path. A higher energy sharpness of the particles contributing to the further particle-optic imaging, and hence a reduction of the effect of chromatic aberrations, is attained by means of the energy filter. So that voltage fluctuations of the applied high voltage also bring about no drift of the image of the beam producer in spite of the dispersion present after complete passage through the filter, the beam producer is imaged, enlarged, in a plane of the filter that is imaged achromatically by the filter into an output image plane. Because of the high dispersion of the dispersive filter as against non-dispersive filters, the particle beam apparatus can be operated at a higher particle energy within the filter, so that the influence of the Boersch effect is reduced in comparison with non-dispersive filters.

Abstract: The invention relates to a particle beam apparatus, in which very low target energies of the particles focused on the object can be set, with good imaging conditions. For this purpose, the beam guiding tube (5), from the anode (4) to behind the objective (6, 7) is at a high potential, which insures that the particles within the beam guiding tube have a high kinetic energy which is independent of the target energy. A braking electrode (9) arranged after the beam guiding tube, together with the object holder (10) and the object arranged thereon, is at a specimen potential UP which deviates from the ground potential and which has the same sign as the cathode potential UK. The specimen potential UP acts as the decelerating potential, by means of which the particles are braked to energies which can be below the energy value determined by the cathode potential UK.

Abstract: A positron source with high intensity and low energy bandwidth and small spatial dimensions, has a positron emitter of high specific activity and, following the positron emitter, a reflection moderator with a hole. The hole diameter on the emitter side of the reflection moderator is smaller than 0.4 mm, preferably below 0.1 mm. Because of the small hole diameter and the small energy spread, the phase space of the positrons coming from the positron source corresponds to the phase space of the electrons emitted by a conventional thermionic cathode. The positron source can therefore be used in a conventional scanning electron microscope, which can be selectively changed over between positron operation and electron operation. Two adjusting units and are provided for adjustment of the positron source.

Abstract: An energy filter, particularly for electron microscopes, in which the setting of different energy bandwidths takes place electron-optically. For this purpose, one or more deflecting systems and one or more transfer lenses are provided at the filter exit. A diaphragm arrangement is arranged in the dispersion plane and has an opening with a stepped edge region. Slit diaphragms with different slit lengths can be simulated by deflection of the electron beam. The deflection of the electron beam effected by the dispersion system(s) perpendicularly to the dispersive direction of the filter is compensated again by a succeeding transfer lens or a further deflecting system, so that an image displacement is also compensated. In a second embodiment, a respective slit edge is arranged in two mutually conjugate spectrum planes. A deflecting system preceding each slit edge, different spectrum portions are filtered out by the two slit edges, according to the excitation of the deflecting systems.