A potential method to detect the orientation of the suspended rod-shaped particles using polarized-light scattering

In situ detection of non-spherical particles is very important for the ocean observatory, because they are the majority of the particles in the sea water. However, many of the current commercial instruments assume the spherical particles. In this paper, we present a method which has the potential to detect the orientation of the suspended rod-shaped particles in the fluid field. We use a simultaneous setup to measure the scattered polarization of the fibers suspended in the water and scan along the fluid field. The experimental results indicate that the intensity and degree of polarization (DOP) will change with the field. To explain it, we build a model by combining the fluid field and the scattering of infinitely long cylinders. The simulation based on the model can recover the main aspects of the experimental results. Then, we give the histogram of DOP of the individual fiber, which implies their orientation distribution. Finally, we suggest a method to retrieve the orientation of the fibers by measuring the full Stokes vector.