DETECTORS FOR LOW-VOLTAGE SCANNING ELECTRON-MICROSCOPY

Two simple electron detectors (low and high take-off angles) for low-voltage scanning electron microscopy were built and tested. They contain large area scintillators with an applied high voltage and are able to detect backscattered electrons with high efficiency. These detectors also can record the sum of backscattered and secondary electrons. The primary beam of the microscope is screened from the scintillator high voltage by grids, which also permit switching from the BSE to the (SE + BSE) mode. The circular symmetry of the grids minimizes the influence of applied potentials on the primary beam. The use of the low and high take-off detectors permits the detection of backscattered electrons emitted from the specimen surface into different ranges of take-off angles.