Spatial correlation of the backscattered acoustic field from fiber reinforced composites

A study of pulsed echography in anisotropic fiber-reinforced composites is presented. Theoretical as well as experimental results are given, and it is shown how the autocorrelation function changes with the orientation of the layers inside the composite, thus pointing out its anisotropy. The spatial coherence properties of speckle in a given medium is important in non-destructive testing, since the reflection of a wave on a small defect will generate a spatially coherent wavelet. Such an echo may be detected among the ambient speckle noise