The electron optical configuration of the novel dual-emission electron spectromicroscope (DEEM) is discussed. The idea of DEEM is based on the concept of the double deflection of the electron beam, initially by the angle +α, through the first concentric spherical deflector and then, after passing through the relay lens, by the angle −α through the second concentric spherical deflector. That novel concept allows parallel observation at two independent imaging units of two different electron optical images: the unfiltered real image and energy filtered electron angular distribution or electron angular distribution and the energy filtered real image. The dispersion of the first deflector lens system is used for the selection of the energy range of the emitted electrons. The relay lens reverses the sign of the distance from the electron optical axis and the angle to this axis of the electron at the input to the second deflector, leading in the ideal case (C_c and C_s equal to 0) to the cancellation of the chromatic and spherical aberrations in the output image plane of the deflector system.

It will be also shown that DEEM instrumentation allows high energy electron sample illumination, which opens new possibilities for chemical mapping and analysis (ESCA, Auger) on a nanometric scale under laboratory conditions.