The origins of the long, high-intensity ribbons that occur when a wave propagates through a multiply scattering random medium are examined. It is shown that such ribbons are initiated when the cumulative phase deviation imposed on the wavefront in the direction of propagation becomes large. Estimates are made of the number of such ribbons that might be encountered in typical cases of multiple scatter, and of their expected separation transverse to the direction of propagation. Finally, it is shown that motion of the source in the transverse direction does not lead to appreciable movement of the ribbons.
Acknowledgements
BJU was suppported by the US Office of Naval Research, Award No. N00014-04-1-0472. MS acknowledges support from a UK DTI eScience grant and the resources of the Cambridge–Cranfield High-Performance Computing Facility.