IMPROVED ESTIMATION OF PHASE ABERRATION PROFILES

Two previous approaches to estimate phase aberration profiles with a s ingle transmit pulse from speckle are examined. The first employs cros s-correlation between signals on all pairs of neighboring elements. In the other, cross-correlation between signals on all elements and the beamsum is used. Here, the two methods are studied in detail, and the advantages and disadvantages of each are discussed. It is shown that c ross-correlations between neighboring elements result in a bias in the estimated phase profile, while correlations to the beamsum result in higher error variance. A new approach combining the two is introduced. Experimental results demonstrate that this new method provides a supe rior phase aberration profile. Furthermore, it is shown that this impr oved phase profile enhances image quality when used to correct both tr ansmitter and receiver.