VASANTHI SIVAPRAKASAM, Jozsef Czege, Jay Eversole, Naval Research Laboratory
Abstract Number: 416 Working Group: Aerosol Physics
Abstract We are developing an experimental setup to measure multi-angle, multi-wavelength polarized scattering measurements of single aerosol particles on-the-fly. Our technique utilizes a novel approach that is a radical departure from conventional approaches to the measurement of polarized scattering data. We will present our experimental approach based on a super continuum light source, an array of optical fibers, an imaging spectrometer and EMCCD camera to instantaneously create a two-dimensional snapshot of scattering data as a function of both wavelength and scattering angle. All the parameters needed for the complete inversion analysis of the particles' size, shape and composition can be measured simultaneously.
To simplify the experimental approach we started our initial measurement on trapped particles instead of the end goal of flowing particles. We use a diode laser at 405 nm to optically trap the particles. We will present some of the polarized elastic scatter measurements from particles held in the trap. As the particles can be held stably for hours, we are able to change the optical configuration (polarizer and retarders) and make multiple Muller matrix indices on the same particle. We have done initial modeling for this measurement at specific angles and the comparison with experimental measurements shows good agreement. We are currently working on expanding our computation capabilities.