Transient analysis of a PVDF Fresnel zone plate

A method of estimating transient beam profiles for polyvinylidene fluoride (PVDF) Fresnel zone plates is presented. The plane and edge wave convolution integral approach is used to calculate the pressure at an arbitrary point due to the transient pressure at the front surface of the zone plate. This technique exploits the circular symmetry of the device to generate an analytic expression for the spatial impulse response. Theoretical estimates of the transient pressure are obtained using a lossy Mason model, which makes it possible to investigate the effects of various excitation signals on the beam profiles during the design phase. The dielectric and mechanical loss parameters used in the model are estimated from simple input impedance measurements of an air-backed, air-loaded sample of PVDF. Model results are presented for a 3-zone Fresnel zone plate, demonstrating the utility of the analysis in excitation signal design