High resolution technique for measuring charge and polarization distributions in dielectrics by piezoelectrically induced pressure step waves (PPS)

In the past, several experimental methods have been developed [1] for the analysis of charge and polarization distributions within dielectrics. The acoustic pressure step method originally proposed by Laurençeau et al. [2] recently could be improved significantly achieving resolutions in the order of a few μm [3, 4]. Instead of using pressure steps generated by a shock tube [2] or pressure pulses originating from short and intense laser excitation [3] our technique for pressure step generation [4] makes use of the transient response of a piezoelectric crystal plate. In the experimental arrangement, c.f. Fig. 1, a 100nsec duration, 400 volt pulse from a 50Ω-cο-axial cable discharge generator is applied to the Schematic representation of the experimental technique. (1) Connection to voltage pulse generator (150psec risetime), (2) Connection to wideband preamplifier and oscilloscope.