Characterization of extended objects with the D.O.R.T. method

The D.O.R.T. Method (Decomposition de l´Operateur de Retournement Temporel) applies to ultrasonic detection and to focusing with arrays of transducers. It generalizes the principle of acoustic time reversal mirrors. It requires the measurement of the inter element impulse responses of the the propagating medium for all pairs of elements in the array. A hermitian matrix called the time reversal operator is deduced from these responses and diagonalized. The eigenvectors provide valuable information on the scattering medium. This method is applied here to the specular echo of an extended object. Experimental and numerical results are compared in the case of a cylinder insonified by a linear array of transducers