Abstract: The invention is directed to an electron energy filter which is assembled from three or four plates placed together in a sandwich-like configuration. The pole pieces are seated on the inner sides of the outer plates and attached thereto. The pole pieces can therefore be produced in pairs so that their outer surfaces match precisely. This assembly is economical and provides a precise manufacture.

Abstract: A transmission electron microscope is disclosed, having an electron-energy spectrometer, a first imaging stage of four electron lenses in front of the spectrometer, and a second imaging stage of two more electron lenses following the spectrometer. The parts are so arranged, according to the disclosed structure, and so operated, according to the disclosed method, that a large range of magnifications can be obtained while the object or specimen to be examined remains in a fixed location, without having to refocus when the magnification is changed. The change in magnification occurs by changing the operation of the first imaging stage. The second imaging stage operates at a substantially fixed magnification, its magnification being changed, if at all, only to accommodate the size of the output image from the second stage to size of the available working area of the detector in the final image plane (fluorescent screen, photographic film, or electronic detector).