Design of sparse array imaging systems

A method for designing sparse periodic arrays is described. Grating lobes in the two-way radiation pattern are avoided by using different element spacings for transmission and reception. The transmit and receive aperture functions are selected such that the convolution of the aperture functions produces a desired effective aperture. A desired effective aperture is simply an aperture with an appropriate width, element spacing and shape such that the Fourier transform of this function gives the desired two-way radiation pattern. Here, the authors apply the effective aperture method to the design of a sparse array for a very high frame rate (1,000 images/s) imaging system. The high frame rate is achieved by using synthetic aperture beam-forming utilizing only a few transmit pulses for each image. To compensate for the resulting loss in signal, the power delivered to each transmit element is increased and multiple transmit elements are used for each transmit burst. By mechanically rocking the array, in a way similar to what is done with an annular array, a three-dimensional set of images can be collected in the time normally required for a single image.

[1]  B. S. Robinson,et al.  Synthetic focus imaging using partial datasets , 1994, 1994 Proceedings of IEEE Ultrasonics Symposium.

[2]  M. O'Donnell,et al.  Array processing for hand-held scanners , 1994, 1994 Proceedings of IEEE Ultrasonics Symposium.

[3]  F.S. Foster,et al.  Optimizing the radiation pattern of sparse periodic two-dimensional arrays , 1996, IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control.

[4]  G. R. Lockwood,et al.  Optimizing sparse two-dimensional transducer arrays using an effective aperture approach , 1994, 1994 Proceedings of IEEE Ultrasonics Symposium.

[5]  S M Gehlbach,et al.  Digital ultrasound imaging techniques using vector sampling and raster line reconstruction. , 1981, Ultrasonic imaging.

[6]  M. O'Donnell,et al.  Synthetic aperture imaging for small scale systems , 1995, IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control.

[7]  Pai-Chi Li,et al.  Optimizing the radiation pattern of sparse periodic linear arrays , 1996, IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control.

[8]  Stephen J. Norton.  Annular array imaging with full‐aperture resolution , 1992 .