Research with nearfield acoustic holography

The main objective of the research was to characterize the potential and limitations of a new sound radiation and intensity vector field measurement technique in regard to both general theory and hardware application. The topics for study included: measurement system considerations (including array construction, data acquisition electronics, calibration of transducer elements, environmental effects, tests of the system accuracy, etc.), plane hologram data processing (including wrap-around error elimination, spatial resolution limits, zoom imaging, array processor algorithms, etc.), cylindrical and spherical data processing algorithms, wideband noise research, and holography for odd-shaped surfaces. The discovery of a technique for reconstructing radiation from odd shaped surfaces represents a major breakthrough, as it allows the use of a plane array of transducers to image the backside of a three dimensional object.