We demonstrate time-resolved measurement of optical phase-space distributio
ns as a new probe for investigating the propagation of light in disordered
media. Phase-space techniques measure the joint transverse position and mom
entum distribution of the scattered light, and are sensitive to the spatial
ly varying phase and amplitude of the field. Using this method we investiga
te tight backscattered from a random medium. The measurements indicate that
the weakly localized component is a phase conjugate of the incident light
field. A new model of backscatter, based on Wigner phase-space distribution
s, elucidates the spatial and angular behavior of the localized and unlocal
ized components.