Comparison of the measurement of polarization distributions by the LIMM and PWP methods

Two different methods of measurement of polarization distributions in piezoelectric materials, the LIMM (laser intensity modulation method) and the PWP (pressure wave propagation) methods, are compared. After briefly describing the two techniques, the authors report measurements made on different PVDF (polyvinylidene fluoride) samples, one with a symmetric and the other with an antisymmetric structure. Although the LIMM method responds to diffusion of heat and the PWP method to the propagation of a pressure wave, the direct observation of the raw data gives in both cases the same information concerning the symmetry of the polarization distribution