  The use of electron mirrors in aberration correction and surface-sensitive
microscopy techniques such as low-energy electron microscopy has been
established. However, in this work, by implementing an easy to construct, fully
electrostatic electron mirror system under a sample in a conventional scanning
electron microscope (SEM), we present a new imaging scheme which allows us to
form scanned images of the top and bottom surfaces of the sample
simultaneously. We believe that this imaging scheme could be of great value to
the field of in-situ SEM which has been limited to observation of dynamic
changes such as crack propagation and other surface phenomena on one side of
samples at a time. We analyze the image properties when using a flat versus a
concave electron mirror system and discuss two different regimes of operation.
In addition to in-situ SEM, we foresee that our imaging scheme could open up
avenues toward spherical aberration correction by the use of electron mirrors
in SEMs without the need for complex beam separators.
