Waves in Random Media

Optical scattering is ever present in the disordered world that surrounds us. It gives rise, for example, to the diffuse blue illumination of the sky and the whiteness of clouds, milk, and paint. Together with emission, absorption, and free propagation, optical scattering governs the light presented to the eye and to photographic and electrooptic imaging systems. In this article, the propagation of light and other parts of the electromagnetic spectrum within disordered media is described. Those aspects of scattering that are common to electromagnetic waves from the radio frequency to the X-rays are emphasized. Many of the illustrations are drawn from microwave measurements for which it is possible to determine both the amplitude and phase of the wave. Since the precise configuration of a random sample is by definition unknown, a statistical approach is required, as is the case in the study of electronic waves in conductors.