H. Taki and T. Sato (Japan)
Ultrasound, hybrid method, reflector mirror, synthetic aperture, phased array, and real-time
Typical acoustic 3-D imaging systems use 1-D transducer array and lenses with fixed focal distance, so the spatial resolution deteriorates in front and behind the focus point. Furthermore, the time resolution is much lower than that of 2-D imaging system. For acoustic real-time 3-D diagnostic imaging systems, we propose a system based on a hybrid array-reflector configuration which realizes high time and spatial resolutions with modest computional load. All elements on a small dense array excite with proper time delays in order to transmit a broad beam similar to that of a single transmitter element. The reflected echo is first focused by a concave reflector, and then received by the same small dense sensor array. Widely distributed images on the array are reconstructed by numerical back projection. With this scheme, images of the whole measuring area can be reconstructed from a single transmit and receive event, which enables a real-time 3-D imaging. The maximum theoretical flame rate is 5000 flames/s, and the number of elements can be reduced to about 1/7 of the dense 2-D array of the synthetic aperture system having the same spatial resolution. This method has higher signal-to-noise ratio than defocused multi-element synthetic aperture methods, overcoming conventional phased array performance.
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