  Scanning probe microscopy (SPM) images of regularly arranged spatially
periodic objects can be processed crystallographically. The resulting
information may be used to remove from the SPM image distortions that are due
to a less than perfect imaging process. The combined effects of these
distortions result in a point spread function that gives a quantitative measure
of the performance of the microscope for a certain set of experimental
conditions. On the basis of highly symmetric calibration samples, the point
spread function of the microscope may be extracted and utilized for the
correction of SPM images of unknowns that were recorded under essentially the
same experimental conditions. We concentrate in this paper on more theoretical
aspects of our method. A blunt scanning tunneling microscopy (STM) tip that
consists of multiple mini-tips with electron orbital dimensions may be
symmetrized on the basis of prior knowledge on the plane symmetry of a
two-dimensional periodic array. This is illustrated with the crystallographic
processing of a STM image of a regular array of fluorinated cobalt
phthalocyanine molecules on graphite and backed up conceptually by simple
simulations.
