Pockels surface potential probe and surface charge density measurement

A surface potential probe based on Pockels sensing technique is developed and applied to surface potential distribution measurement on insulating material. The probe consists of a super luminescent diode, a Pockels crystal, a polarized beam splitter, a View the MathML source wave plate and optical fibers. As the detecting part of the probe is isolated from a grounded electrode, this probe can be placed closer to the measured object. The resolving power is View the MathML source which is equivalent to the twice size of the detecting part. The modulation technique is introduced to this probe and the minimum sensitivity reaches View the MathML source. This probe is applied to the measurement of the potential distribution on an insulating material just after occurrence of a surface discharge. From this measured potential profile, the distribution of surface charge density is computed through a surface charge method.