Measuring the Three-Dimensional Volume Scattering Functions of Microsphere Suspension: Design and Laboratory Experiments

The measurement of the volume scattering function (VSF) of suspended particles is an ongoing research topic since it has the potential to provide a rapid, nondestructive means of analyzing hydrosols. Despite the success of scattering theory, the measurement of multidirectional scattering intensity distributions over a wide, continuous range of scattering angles and multiple scattering planes, which is described by a three-dimensional VSF (3D VSF), has proven to be difficult. To measure the 3D VSF of submicron particles suspended in water, a measurement approach is proposed, built and tested with several standard submicron particles with diameters ranging from 60 nm to 1 mu m. The experimental results indicate that the proposed setup can obtain an accurate 3D VSF for scattering angles from 21 degrees to 160 degrees and azimuthal angles from 1 degrees to 179 degrees. Comparisons between the experiment and theory show a high level of consistency for particles with diameters less than 200 nm. The variation in the VSF in response to the polarization direction of the incident light is also discussed. Both the experiment and theory show the potential of the device to detect the 3D VSF of marine submicron biological particles.