Using signals scattered from diffuse inhomogeneities to correct for phase aberrations caused by a phase-screen far from the transducer

The phase and the amplitude of an acoustical wave will be disturbed if the wave propagates through human tissue. These distortions reduce the quality of medical ultrasound images. Several scientists have suggested methods to do corrections. So far, all presented methods have at least one important weakness. The methods based on time delay focusing do not correct well for distortions caused by phase aberrations introduced far from the transducer. The time reversal mirror (TRM) method does not have this limitation, but it needs a point scatterer to reflect the emitted wave. In this paper, a way to combine the best of the two methods are presented. The suggested method is based on delay and amplitude focusing (DAF).