Abstract
Progress in designing and constructing an atmospheric or environmental scanning electron microscope (SEM) is reported. The introduction of vacuum pumping between the objective and pressure limiting aperture has allowed the use of relatively large pressure limiting apertures, i.e., up to 57 μm for operation at atmospheric pressure or up to 400 μm for operation at saturation water vapour pressure and room temperature. The imaging obtained has been considerably improved by these developments. The first part of experimentation and analysis on the vacuum characteristics of the new system together with different detection configurations is also presented.