Spatially and Temporally Varying Insonification for the Elimination of Spurious Detail in Acoustic Transmission Imaging
Acoustic transmission images obtained with spatially coherent insonification are often difficult to interpret since complex interference patterns are superimposed on pertinent object details.
In this paper we report results obtained with the SRI real-time ultrasonic imaging system, using a new insonification technique. Theoretical considerations for the design of a diffuse insonifier are presented along with experimental results demonstrating a significant reduction in the problems of nonuniform insonification and of frame-to-frame variations of the sound field. The diffuse insonification is essentially uniform in space and time, and free of near-field diffraction patterns. The effects of out-of-focus objects have, by and large, been eliminated. Images of biological objects exhibit less contrast with diffuse insonification but provide a more faithful representation of object structures. The implications of this result with regard to the dynamic range capabilities of the imaging system are discussed.
KeywordsFocal Plane Sound Field Imaging Lens Angular Spectrum Acoustic Image
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