  Experimental characterization of blood flow in living organisms is crucial
for understanding the development and function of cardiovascular systems, but
there have been no techniques reported for snapshot imaging of thick samples in
large volumes with high precision. We have combined computational microscopy
and the diffraction-free, self-bending property of Airy beams to track
fluorescent beads with sub-micron precision through an extended axial range (up
to 600 $\mu$m) within the flowing blood of 3 days post-fertilization (dpf)
zebrafish embryos. The spatial trajectories of the tracer beads within flowing
blood were recorded during transit through both cardinal and intersegmental
vessels, and the trajectories were found to be consistent with the segmentation
of the vasculature recorded using selective-plane illumination microscopy
(SPIM). This method provides precise spatial and temporal measurement of 3D
blood flow with potential for enhanced understanding of fundamental dynamics,
such as measurement of wall shear stress or of cardiovascular disease.
