Detector System for Three-Dimensional Imaging in the Variable Pressure/Environmental SEM

The authors developed a method of three-dimensional surface reconstruction, which takes advantage of the angular distribution of backscattered electron emission to obtain a digital map of surface elevations. Such quantitative information about the surface topography is obtained by digital processing of four input images acquired from four electron detectors. The method was adapted to environmental conditions by means of the vacuum-detector equipment applicable for a standard scanning electron microscopy. The main part of the equipment is the vacuum-detector head containing the intermediate vacuum chamber with a semiconductor backscattered electron detector inside. The detector captures a zenith backscattered electron fraction passing through the throttling aperture placed closely to the sample at the distance comparable to the aperture diameter (0.6 mm). The system was dedicated to the investigations of solid nonconductive samples at pressures < 10 hPa but it has already been supplemented with a gaseous directional backscattered electron detector which can work at a distance of a few mm to be safe for biological samples