Title: Numerical prediction of the piezoelectric transducer response in the acoustic nearfield using a one-dimensional electromechanical finite difference approach,
Abstract: We present a simple electromechanical finite difference model to study the
response of a piezoelectric polyvinylidenflourid (PVDF) transducer to
optoacoustic (OA) pressure waves in the acoustic nearfield prior to thermal
relaxation of the OA source volume. The assumption of nearfield conditions,
i.e. the absence of acoustic diffraction, allows to treat the problem using a
one-dimensional numerical approach. Therein, the computational domain is
modeled as an inhomogeneous elastic medium, characterized by its local wave
velocities and densities, allowing to explore the effect of stepwise impedance
changes on the stress wave propagation. The transducer is modeled as a thin
piezoelectric sensing layer and the electromechanical coupling is accomplished
by means of the respective linear constituting equations. Considering a
low-pass characteristic of the full experimental setup, we obtain the resulting
transducer signal. Complementing transducer signals measured in a controlled
laboratory experiment with numerical simulations that result from a model of
the experimental setup, we find that, bearing in mind the apparent limitations
of the one-dimensional approach, the simulated transducer signals can be used
very well to predict and interpret the experimental findings.