Electron Energy Analysis by a Cylindrical Magnetic Lens

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Abstract
Cylindrical magnetic lenses were developed with the aim of energy analysis of electrons. A set magnetic pole-pieces with rectangular apertures was inserted into the bore of the intermediate lens of a usual electron microscope and was used as an analyzer lens. It has a large chromatic aberration constant for off-axial rays when it was energized to a lens strength k≃√3. An image of specimen was formed by the objective lens on a slit plane of the field limiting aperture. The energy of electrons which had passed through the slit was analyzed by the analyzer lens and the energy loss spectrum of the limited image was obtained perendicularly to the slit length with an energy resolution of 1 eV at 80 kV. Lens action of the analyzer lens and experimental procedures for energy analysis are described in details. Some results of energy analysis are shown for several specimens of various thicknesses. The energy resolution and position resolution of this analyzer are discussed for a few practical cases.