In-column detector for particle-optical column

摘要

The invention relates to an in-column back-scattered electron detector, the detector placed in a combined electrostatic/magnetic objective lens for a SEM. The detector is formed as a charged particle sensitive surface, preferably a scintillator disk (406) that acts as one of the electrode faces (110) forming the electrostatic focusing field. The photons generated in the scintillator are detected by a photon detector (202, 408), such as a photo-diode or a multipixel photon detector. The objective lens may be equipped with another electron detector (116) for detecting secondary electrons that are kept closer to the axis. A light guide (204, 404) may be used to offer electrical insulation between the photon detector and the scintillator.