How the SEM Works

The SEM uses electrons instead
of light to form skematicworksan image. A beam
of electrons is produced at the top
of the microscope by heating of a
metallic filament. The electron beam
follows a vertical path through the
column of the microscope. It makes
its way through electromagnetic
lenses which focus and direct the
beam down towards the sample.
Once it hits the sample, other
electrons
(backscattered or
secondary) are
ejected from the
sample.

Detectors collect the secondary
or backscattered electrons, and
convert them to a signal that is
sent to a viewing screen similiar
to the one in an ordinary television,
producing an image.