Digital holographic microscopy implementation for capillary filling measurements in nanoporous materials

We report the implementation of lensless off-axis digital holographic microscopy as a non-destructive optical analyzer for nano-scale structures. The measurement capacity of the system was validated by analyzing the topography of a metallic grid with ≈150nm thick opaque features. In addition, an experimental configuration of self-reference was included to study the dynamics of the capillary filling phenomena in nanostructured porous silicon. The fluid front position as a function of time was extracted from the holograms, and the typical square root of time kinematics was recovered. The results shown are in agreement with previous works on capillary imbibition in similar structures and confirm a first step towards unifying holographic methods with fluid dynamics theory to develop a spatially resolved capillary tomography system for nanoporous materials characterization.