Enhanced backscattering of partially coherent light.

The backscattering enhancement of light from random media is analyzed for situations in which the scatterers are illuminated with spatially partially coherent light. The effect of coherence is incorporated into the existing theories by use of the angular correlation description for the illuminating light field. When the area of illumination is infinite, an analogy to the van Cittert-Zernike theorem leads to the expression for the intensity distribution that is given by the sum of backscattered intensities, each of which would arise from each incident plane-wave component of the angular spectrum. It is shown that the backscattering cone is partially suppressed and deformed owing to breaking of the time-reversal symmetry of mutiple-scattering paths.