Scattering Investigation Based on Acoustical Holography.

The objective of this research is to investigate sound scattering by an object using a two-surface measurement technique that separates the incident field and the scattered field. The separation technique is developed in cartesian and cylindrical coordinates. The decomposition method in the cartesian coordinate system is based on the principle that any wave form can be decomposed into plane-wave components by using a two dimensional spatial Fourier transform. For the cylindrical coordinate system, a two plane separation technique is based on decomposing the sound field into cylindrical waves. Numerical simulations are performed and the effect of various parameters are investigated. Specifically, the distance between two measurement surfaces, the distance between measurement points, and the aperture size are investigated. In addition, experimental studies were conducted inside an anechoic chamber with a baffled loudspeaker as a source, illuminating four different scatterers. The decomposed scattered field is then used to estimate the far-field target strength. The experiments demonstrate the feasibility of the field separation technique.