Influences of probe geometry and experimental errors on spatial resolution of surface charge measurement with electrostatic probe

When an electrostatic probe is used for surface charge measurement on an insulating plate with constant thickness or a long insulating pipe, the configuration of the measuring system is regarded as shift-invariant and the relation between the surface charge density and the probe output can be treated in the spatial frequency domain through Fourier analysis. In the inverse calculation from the probe output to the charge distribution, a Wiener-filter technique is effectively used to suppress the excessive amplification of the noise. Influences of the probe geometry and experimental errors on the spatial resolution of the total measuring system, including the restoration process with the Wiener filter, are quantitatively discussed through the analysis of transfer characteristics in the spatial frequency domain.