Interference patterns of directed waves

Oded Agam

Department of Physics, Hebrew University.

In this talk I will discuss the old problem of waves propagating in a disordered medium and experience small angle scattering - the so called "directed waves" problem. This issue is of great scientific and technological importance. It is, for instance, relevant for adaptive optics used in terrestrial telescopes; for satellite communication; lasers, and medical imaging. Yet, only recently, the interference patterns of directed waves have been correctly characterized. I will show that, in contrast with previous theories, correlations in the speckle pattern of directed waves experience slow power law decay, and a sign change. A qualitative explanation of this behavior will be given, using the Langevin approach in which diffraction is mimicked by a random spatial noise.