Use of laser-generated acoustic pulses to measure the electric field inside a solid dielectric

We describe a technique for measuring the electric field inside solid dielectrics and apply it to a polymethylmethacrylate sample. The technique uses a laser-generated acoustic pulse to deform the sample inhomogeneously in a nondestructive, nonperturbing manner. From the electrical response of the sample during deformation, the macroscopic electric field as a function of position may be calculated. We achieved a sensitivity of 5×104 V/m and a spatial resolution of 50 μm in a 3-mm-thick sample.