ASA 130th Meeting - St. Louis, MO - 1995 Nov 27 .. Dec 01

4pSP8. Acoustic imaging with radiation imaging operators.

Mohammed I. Raza

Dept. of Elect. Eng., Univ. of Missouri-Rolla, Rolla, MO 65401

Richard E. DuBroff

Thomas J. Herrick

Univ. of Missouri-Rolla, Rolla, MO 65401

A differential operator has been formulated, which can be used to remotely detect boundaries and position of objects from remote data. The operator has been called the radiation imaging operator (RIO). The RIO is composed of local characteristic parameters and local derivatives of the acoustic wave. After operating on the wave distribution, the output gives a minimum at the boundary of the object, when the correct values of the characteristic parameters are used. The RIOs are developed from radiation boundary conditions (RBCs) and the relevant material boundary conditions (MBCs). The RBCs were formulated [B. Engquist and A. Majda, Math. Comput. 31, 629--651 (1977)] to simulate the propagation of out-going waves without any significant reflection at the truncating boundary. The MBCs are in the form of Dirichlet and Neumann boundary conditions. A finite-difference time-domain algorithm is implemented to image objects using the discretized RIO, where the shape and location of object is not known. The imaging technique has been found to be robust and tolerant to a reasonable amount of noise.