Image Contrast and Signal Processing

The most important topographic contrast mode with secondary electrons is a consequence of the dependence of the SE yield on the local tilt of the specimen surface. A fraction of the SE signal is excited by the primary electron probe and carries high-resolution information since the exit depth of the SE is small. Another fraction of poorer resolution is excited by the BSE. If, instead of using the conventional SE detector, the SE are sorted according to their exit momenta, a more quantitative interpretation of the topography may be possible.