| Summary: | The oriented emission of photons from an excited population of molecules, causing luminescence anisotropy, is subject to stochastic processes in a fluid. In addition to the well-known lateral Brownian motion, the population is exposed to random rotational processes as well, leading to a depolarization of the luminescence signal. In contrast, the rotation induced by a flow field, the vorticity, is a deterministic process. This rotation can be expressed in terms of a modified emission distribution function of the population. A model is developed to link these deterministic rotations to polarized intensity signals in an experiment. Analytical results of instantaneous and time-integrated intensity signals are provided, incorporating rotational Brownian motion and luminescence lifetime. The number of intensity signals is restricted to an experimentally feasible case, limiting the measurable results to the magnitude of vorticity components. The sensitivity regarding Brownian rotational motion and luminescence lifetime is evaluated. Next to the simplified solutions for 1- and 2-component vorticity fields, a minimization problem is presented to numerically solve the full problem of a 3-component vorticity field influencing the emission behavior. The developed Python toolbox is validated with a synthetic signals of a round turbulent jet.
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