In the present study, a digital holography microscope has been developed to study instantaneous 3D velocity field in a square channel of 1000 × 1000 $\mu𝑚^2$ cross-section. The flow field is seeded with polystyrene microspheres of size $d_p = 2.1$ 𝜇m. The volumetric flow rate is set equal to 20 𝜇l/min. The instantaneous 3D velocity field is obtained by correlating the particles obtained from the 3D numerical reconstruction of holograms using particle tracking velocimetry (PTV).
