Synthetic Aperture Echo Imaging
Mehrdad Soumekh Principal Investigator
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The objectives of this investigation are to develop inversion principles, data acquisition strategies, and information processing algorithms for an echo imaging system that utilizes the motion of a single element transducer (SET) to synthesize the effect of a phased array with a size equal to the path length that the SET traverses. A mobile SET, with a dimension much smaller than a phased array's size, brings flexibility in data acquisition and processing for echo imaging systems. Synthetic aperture echo imaging also opens ways for imaging an object that cannot be studies with phased arrays due to constraints imposed by the object's anatomy. Unlike the dynamic focusing inversion used in conjunction with stationary phased arrays, the proposed inversion produces an image scene by integrating the recorded echoed signals at the available coordinates of the mobile SET that possesses a wide-beam radiation pattern. The investigation includes modifying an inversion developed for a translational or rotational SET for practical echo imaging problems that arise in diagnostic medicine, remote sensing and non-destructive testing. The required sampling and processing issues associated with the recorded data as well as the resolution anticipated in a given synthetic aperture echo imaging problem are also studied. The result will be used to develop efficient data collection strategies for two-dimensional and three-dimensional echo imaging systems. Sub-band processing of the available spatial frequency data to reduce the computational time for image reconstruction is also being pursued.