Estimation of flow rate and direction of medium with low scattering coefficient via linear polarization measurement

Many biological systems involve flow of various types of liquids. Estimation of the rate and direction of the flow is highly important for a large number of bio-medical related applications. The working point discussed in this paper involves a medium with a relatively low scattering coefficient such that the polarized light going through it is not depolarized, but rather modifies its polarization state instead. An experimental validation is presented, which shows that illuminating flow in a medium with linear polarized light, and measuring the change in polarization state at the output of the medium, can correlate highly with the direction and flow rate through that medium. By inspecting the spatial shape change in the spot of light, and the change of polarization state in relation to different integration times as well, the direction and flow rate can be fully extracted. (C) 2012 Elsevier Ltd. All rights reserved.