Flow measurements through scattering samples using self-mixing interferometry with a laser diode

The study presented demonstrates the ability of the self-mixing interferometry configuration with a laser diode to measure flow through scattering media. A flow model has been used based on a 1.5mm-diameter tube covered with layers of scattering media. The laser intensity power spectrum has been obtained when changing the flow value and the thickness of the layer placed on top of the tube. Different data processing algorithms have been compared including first moment, normalized first moment, RMS, and Lorentzian and exponential curve fitting parameters. It was found that an exponential curve in semi-logarithm scale well describe the spectrum and can be best used when monitoring flow under layers of up to 1.1mm in thickness.