Non-destructive space-charge and polarization tomography with thermal pulses

Non-destructive, three-dimensional imaging of space-charge and polarization distributions in elec-tret materials has been implemented by means of laser-induced thermal pulses. In pyroelectric films of poled poly(vinylidene fluoride), images of up to 45 x 45 pixels with a depth resolution of less than 0.5 |xm and a lateral resolution of 40 |xm were recorded, the latter being limited by fast thermal diffusion in the absorbing metallic front electrode. Initial applications include the analysis of polarization distributions in corona-poled piezoelectric sensor cables and the detection of patterned space-charge distributions in polytetrafluoroethylene films.