  We exploit low spatial coherence illumination to dephase time-reversed
partial waves outside its finite coherence area, which virtually creates a
controllable coherence volume and isolates the minimal number of scattering
events from higher order scattering in enhanced backscattering (EBS, also known
as coherent backscattering) of light. We report the first experimental evidence
that the minimum number of scattering events in EBS is double scattering in
discrete random media, which has been hypothesized since the first observation
of EBS of light. We discuss several unique characteristics and potential
applications of low-coherence EBS in weakly scattering random media.
