Investigating the absolute phase information in acoustic wave resonance scattering

The aim of this work is to investigate the absolute phase information in resonance acoustic scattering by spheres and cylinders and place this work in the broader context of scattering in which the properties of the magnitude and (processed) phase have been examined in a more general way than in the classical resonance scattering theory (RST). Here, comparisons are made between the classical and modified RST formalisms of acoustic resonance scattering. Experimental and theoretical backscattering form functions are obtained and discussed. It is shown that the magnitude and processed (unwrapped) phase can be correctly obtained through the classical RST, suggesting that the modified RST formalism offers little new practical advantage. Furthermore, the absolute phase is shown to be very sensitive to object's resonances, suggesting that the unwrapped phase may be considered as an efficient tool, along with the magnitude information, to carry out remote (active) classification of targets in underwater acoustics applications. The combination of absolute phase information with the magnitude data offers a complementary advantage in the identification of resonances from cylinders and spheres.