In-lens magnetically filtered detector for scanning electron microscope

Electrons scattered with zero energy loss from a solid target in the high-field region of a condenser-objective lens are confined within a region having a well-defined outer boundary by the focusing field of the lens. An energy-filtering detector has been built in which the fastest scattered electrons are selected by a curved knife-edge just inside this boundary and then forward-scattered onto a scintillator at +6kV. The resulting images are compared with secondary electron and backscattered electron images obtained using conventional detectors.