Imaging of specimens at optimized low and very low energies in scanning electron microscopes

The modern trend towards low electron energies in scanning electron microsc opy (SEM), characterised by lowering the acceleration voltages in low-volta ge SEM (LVSEM) or by utilising a retarding-field optical element in low-ene rgy SEM (LESEM), makes the energy range where new contrasts appear accessib le. This range is further extended by a scanning low-energy electron micros cope (SLEEM) fitted with a cathode lens that achieves nearly constant spati al resolution throughout the energy scale. This enables one to optimise fre ely the electron beam energy according to the given task. At low energies, there exist classes of image contrast that make particular specimen data vi sible most effectively or even exclusively within certain energy intervals or at certain energy values. Some contrasts are well understood and can pre sently be utilised for practical surface examinations, but others have not yet been reliably explained and therefore supplementary experiments are nee ded.