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Off-axis scatterer filters for improved aberration measurements

Successful adaptive imaging requires accurate measurements of the aberration profile across the array surface. A spatial filter is proposed in this work to obtain more accurate aberration measurements by suppressing wavefronts from off-axis scatterers. Application of these filters to the RF signals of the individual elements rejects wavefronts arriving from angles other than the look direction and results in an increase in element-to-element correlation. Off-axis scatterer filtering reduced the amount of residual error after phase correction by up to 36% on a 1/spl times/192 array and as much as 21% for a 8/spl times/96 array. Contrast measurements show that lesion contrast can increase up to 18% with this method.