Properties comparison of three HF (50 MHz) single-element transducer radiation patterns with different focusing principles
Sean Toffessi Siewe, Samuel Callé, Aline Banquart, F. Ossant, Jean‐Marc Grégoire, Franck Levassort
Abstract
This numerical study compares the acoustic performance of three focalization principles (using a concave piezoelectric element, a lens, or a Fresnel Zone Plate) for a high-frequency (50 MHz) PVDF-based single-element transducer. A pseudo-spectral time-domain method was used to simulate the ultrasound wave propagation in water and to deduce acoustic properties in the focal zone. The focal distance was investigated between 10-20 mm with a step of 1 mm. The external diameter was identical for all configurations and fixed at 6 mm. The results showed a similar behavior between the concave shape and acoustic lens in terms of spatial resolution. However, the comparison showed a significant loss in sensitivity (-22 dB) for the FZP technique mainly due to the large bandwidth at -6 dB (27 MHz) of the electric excitation signal. But, with low bandwidth excitation signal, the simulation showed better performance in the focal zone with FZP transducer and a sensitivity difference with the two others configurations in the range 4.5-8.5 dB.