A method for detecting charge defect spots (CDSs) on a chargeable surface
is provided, including charging the chargeable surface to receive and
hold a first voltage charge, spacing a surface of a scanner probe a
distance from the chargeable surface, the scanner probe having a
diameter, and biasing the scanner probe to a second voltage charge within
a predetermined voltage threshold of the first voltage charge, wherein a
parallel plate capacitor is established with the chargeable surface and a
dielectric substance between the scanner probe and the chargeable
surface. The method further includes reading with the scanner probe
potentials associated with charges induced from the applied charges and
any CDSs on the chargeable surface, including sensing the potentials and
generating a signal corresponding to the sensing, applying a reference
charge to the chargeable surface, and determining the potential of a CDS
on the chargeable surface based on the scanner probe readings and at
least one of the applied charges, which includes correcting for
non-uniform charge distribution caused by a point-like nature of the CDS
on the chargeable surface.