A new detection configuration using the gaseous detector device in the environmental scanning electron microscope (ESEM) is demonstrated. First, the pressure‐limiting aperture (PLA1) is used simultaneously as a biased electrode to collect the ionization current produced in the gaseous environment of the microscope. Second, a wire electrode is placed above the pressure‐limiting aperture, and it is shown that enough signal from the specimen escapes through the aperture to produce satisfactory images. These detection configurations allow the use of high specimen chamber pressures. Copyright © 1990 Foundation for Advances in Medicine and Science, Inc.
