Spatial coherence of forward-scattered light in a turbid medium

We study spatially coherent forward-scattered light propagating in a turbid medium of moderate optical depth (0-9 mean free paths). Coherent detection was achieved by using a tilted heterodyne geometry, which desensitizes coh erent detection of the attenuated incident light. We show that the degree o f spatial coherence is significantly higher for Light scattered only once i n comparison with that for multiply scattered light and that it approaches a small constant value for large numbers of scattering events. (C) 1999 Opt ical Society of America [S0740-3232(99)01104-7].