Measurement of fibre potentials in a scanning electron microscope

A technique is described which uses a scanning electron microscope to measure the electrical potential on a cylindrical filament such as a metal wire or organic polymer fibre. Two images of the filament and its background are required: one with the filament charged to the unknown potential and one in an uncharged condition (or with the filament removed). Measurements made directly on Stereoscan micrographs were used together with calculations of electron deflection paths to determine filament potentials from 1000 to 18 000 V. Charge densities measured on organic polymer fibres were as high as 2 × 10 12 electrons per cm 2 .