Digital interferometry: techniques and trends for fluid measurement

Interferometric based measurement techniques have long played a significant role in enabling insight and understanding into the flow and heat transfer processes in a wide range of fluid flow situations. In recent years, with the advent of digital processing techniques, full field quantitative data can be obtained from interferometric data with relative ease and a high degree of accuracy. However, these developments seem not to have percolated through to experimental fluids practitioners. This paper sets out to review the various processing and acquisition techniques for quantitative and qualitative measurement using interferometry. Full field phase measurement interferometry (PMI) and differential interferometry (DI) are discussed. PMI is demonstrated for diffusing mixing in a mini-channel and DI is demonstrated for heat transfer measurement in a convecting fluid.