Ultrasonic imaging using two dimensional cross-correlation function

Conventional imaging techniques make the assumption that each scatterer is a source of a spherical wave propagating with a constant velocity towards the transducer array. Then, the processing reduces to the recognition of each of these spherical waves. Such a recognition process may be achieved by the cross correlation techniques but usually cross-correlation is only computed versus time variable. In some particular geometry problems, because of invariance by translation of the Green function, the cross correlation technique is still applicable but computations should be realized versus two variables: time and one spatial variables. In this paper, the two dimensional (2D) cross-correlation technique is demonstrated and used to image scatterers located inside a rectangular wave guide. In addition to the calculation flexibility, the ultrasonic images obtained present a better spatial resolution than that obtained using conventional techniques. Experimental results show that the spatial resolution is 5 times thinner than the usual one