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Updated: Sep 28, 2026

Analyzing Mixing Inhomogeneity in a Microfluidic Device by Microscale Schlieren Technique
Published on: June 12, 2015
Optical measurement of concentration gradient near miscible interfaces
N Rashidnia1, R Balasubramaniam
1National Center for Microgravity Research on Fluids and Combustion, NASA Glenn Research Center, Cleveland, Ohio 44135, USA.
Abstract:
A common path interferometer (CPI) system was developed to measure the diffusivity of transparent liquid pairs. The CPI is an optical technique that can be used to measure changes in the gradient of refractive index of transparent materials. The CPI is a shearing interferometer that shares the same optical path from a laser light source to the final imaging plane. Molecular diffusivity of liquids can be determined by using physical relations between changes in optical path length and liquid phase properties. In this paper, we present results obtained when the diffusivity depends on the local concentration of the miscible fluids.
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