The Inversion Algorithm of Non-Invasive Surface Potential Measurement Based on Wiener Filter

Traditional measurement schemes of surface potential are only suitable for short-circuit stage, where the surface potential and surface charge are located on the same surface of the test sample. The non-invasive measurement enables online measurement of surface potential by applying high voltages on one side of the test sample and measured surface potential on the other side, and the sample thickness should be considered when constructing the inversion algorithm from surface potential to surface charge. In this paper, the inversion algorithm in needle-plate configuration is calculated with the analytical method and optimized by the Wiener filter. The Wiener filter weakens the negative oscillation in the inversion matrix, and the surface charge distribution after inversion conforms to the actual situation, rather than the speckle distribution calculated by the inversion algorithm without the Wiener filter.