Two-Dimensional Measurement of Electrical Surface Charge Distribution on Insulating Material by Electrooptic Pockels Effect

Abstract

The image produced by a surface electrical discharge and the amount of charge were studied by the Pockels effect of a BSO single-crystal cell. The cell has only one transparent metal plate electrode which is located at the rear surface of the cell and is grounded. Electrical surface charges are placed on the other surface by a high-voltage discharge between the rear plate electrode and a point electrode. The applied impulse voltage on a 1.0-mm-thick cell had a peak of approximately 6 kV. An 8-mm-diameter discharge figure was obtained using a charge-coupled device (CCD) camera which was placed behind the rear electrode. The maximum charge density on the cell calculated from image processing was 70 nC/cm². Using circular polarized incident light, the polarity of the surface charge was determined. These results are closely related to the charge densities obtained by other methods.