  Holographic particle image velocimetry allows tracking particle trajectories
in time and space by means of holography. However, the drawback of the
technique is that in the three-dimensional particle distribution reconstructed
from a hologram, the individual particles can hardly be resolved due to the
superimposed out-of-focus signal from neighboring particles. We demonstrate
here a three-dimensional volumetric deconvolution applied to the reconstructed
wavefront which results in resolving all particles simultaneously in
three-dimensions. Moreover, we apply the three-dimensional volumetric
deconvolution to reconstructions of a time-dependent sequence of holograms of
an ensemble of polystyrene spheres moving in water. From each hologram we
simultaneously resolve all particles in the ensemble in three dimensions and
from the sequence of holograms we obtain the time-resolved trajectories of
individual polystyrene spheres.
