METHOD OF MEASURING SURFACE ELECTRIC CHARGE-DISTRIBUTIONS - COMMENT

In order to determine what effectively may be measured by means of the studied method [1], we have tried to define precisely the various qua ntities involved. In the first part, considering only the two dimensio ns x and y taken into account in [1], we display arguments in order to point out some difficulties. So we show that the advised method is ab le to deliver a deformed image only of the surface charge density sigm a(y) carried by the dielectric, the relative deformation being the les s pronounced the larger the characteristic length Y of sigma(y) is wit h respect to the distance DELTAx = a between the probe and the surface of the dielectric. In the second part we generalize our results by co nsidering a 3-dimensional problem where the surface charge density is of the type sigma(y, z).