We propose a novel backscatter holographic imaging system, as a compact and effective tool for 3D near-wall flow diagnostics at high resolutions, utilizing light reflected at the solid-liquid interface as a reference beam. The technique is fully calibrated, and is demonstrated in a densely seeded channel to achieve a spatial resolution of near-wall flows equivalent to or exceeding prior digital inline holographic measurements using local tracer seeding technique. Additionally, we examined the effects of seeding concentration and laser coherence on the measurement resolution and sample volume resolved, demonstrating the potential to manipulate sample domain by tuning the laser coherence profile.
Bibliographical noteFunding Information:
Office of Naval Research (Program Manager, Dr. Thomas Fu) under Grant No. N000141612755 and McKnight Award from University of Minnesota.
Office of Naval Research (Program Manager, Dr. Thomas Fu) under Grant No. N000141612755 and McKnight Award from University of Minnesota. The authors would like to thank Kevin Mallery for his assistance in the data processing and Brandon Shadakofsky for his help with the channel flow experiment.