  Three-dimensional mapping of surface structures is important in a wide range
of biological, technological, healthcare and research applications, including
taxonomy, microfluidics and fabrication. Neutral helium atom beams have been
established as a sensitive probe of topography and have already enabled
structural information to be obtained from delicate samples, where conventional
probes would cause damage. Here, we demonstrate empirical reconstruction of a
complete surface profile using measurements from a scanning helium microscope
(SHeM), using the heliometric stereo method and a single detector instrument
geometry. Results for the surface profile of tetrahedral aluminum potassium
sulphate crystals demonstrate the areas of surfaces and facet orientations can
be recovered to within 5% of the expected values.
