Richard L. Weaver, Oleg I. Lobkis, 2008. "Diffuse fields in ultrasonics and seismology", Seismic Interferometry: History and Present Status, Kees Wapenaar, Deyan Draganov, Johan O.A. Robertsson
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We review the history of diffuse ultrasonic waves in solids with emphasis on recent developments in field-field correlations and their identification with Green’s function. The basic principles appear to be well understood now, and the identity between these two waveforms has been proven under a variety of assumed conditions that guarantee a diffuse field. Promise for practical passive imaging is good; nevertheless, measurements sometimes fail to fully agree with theory. We ascribe this in some cases to incomplete convergence — insufficient amounts of data have been processed. In other cases, it is probably because of a lack of perfect diffuseness; ambient nonmultiply scattered fields are often not equipartitioned and imperfectly diffuse.