ASA 125th Meeting Ottawa 1993 May

2pPA7. Nondestructive evaluations in multiple scattering media.

Christian Vanneste

Lab. de Phys. de la Matiere Condensee, CNRS URA 190, Univ. de Nice---Sophia Antipolis, Parc Valrose, 06108 Nice Cedex 2, France

Shechao Feng

Univ. of California, Los Angeles, CA 90024

Didier Sornette

Univ. de Nice---Sophia Antipolis, Nice, France

Due to its tendency to scramble the structural information, multiple scattering blurs the distinction between different materials containing different kinds and numbers of defects, or their configurations, beyond the scattering mean-free-path distance from the observation point, thereby rendering most random systems cloudy in appearance and opaque in the sense of structure delineation. However, it has recently been shown theoretically [Feng and Sornette, J. Acoust. Soc. Am. 90, 1742--1747 (1991)] that imaging of a new defect in a multiple scattering medium is in principle possible using speckle pattern correlations. Extensive numerical simulations and analytical calculations were performed to demonstrate the feasibility of detecting a new crack in a single given sample already containing many cracks using speckle pattern averaging technique at many different frequencies. Potential applications of this approach can be found in medical and industrial imaging needs in highly scattering systems.