High frame rate imaging with diverging beam transmission and fourier reconstruction

A high frame rate imaging method where a limited diffraction beam is used in transmission and received echo signals are processed with both temporal and spatial fast Fourier transforms to reconstruct images has been developed previously. However, this method has a limitation that objects to be imaged are illuminated only within the projection of transducer aperture. To reconstruct images of a large field of view at a large distance, multiple transmissions are required to illuminate the entire objects and thus image frame rate may be reduced. To overcome such a limitation, in this paper, diverging beams that can illuminate a larger area in one transmission are used while the same temporal and spatial fast Fourier transforms as in the high frame rate imaging method are used to reconstruct images. Results show that images reconstructed with diverging beams of a diverging angle up to 15 degrees in transmission have a reasonable image quality as compared to that of images reconstructed with a limited diffraction beam in transmission (in theory, limited diffraction beams have 0 degree diverging angle).