AAAR 33rd Annual Conference
October 20 - October 24, 2014
Rosen Shingle Creek
Orlando, Florida, USA
Abstract View
Wavelength Resolved Polarized Elastic Scattering Measurements from Single Particles
Jozsef Czege, VASANTHI SIVAPRAKASAM, Jay Eversole, Naval Research Laboratory
Abstract Number: 62 Working Group: Aerosol Physics
Abstract We provide an update on the progress of our project to investigate the polarimetric scattering signatures of aerosol particles. Our goal is to search for correlations of angular and polarimetric elastic scatter patterns with morphological categories based on individual particle structure and composition, and to evaluate application of these types of correlation for discrimination between man-made and naturally occurring aerosol particles. In order to implement this type of capability, we have developed an experimental arrangement to measure multi-angle, multi-wavelength polarized scatter from single aerosol particles suspended in a sample flow in essentially real-time. Our experimental approach is based on a super-continuum light source, an array of optical fibers, an imaging spectrometer and camera to simultaneously acquire a two-dimensional snapshot of scattering data. Preliminary Mueller matrix measurements have been made from individual particles held in an optical trap (at 405 nm), or on particles that slowly drift into the collection volume. We have done modeling for these measurements at specific angles and the comparison with experimental measurements shows good agreement. Initial measurements were conducted in the visible region, 450 nm to 900 nm, but recently we have extended the range of the measurements to encompass the IR region, 1000 to 1700 nm as well. We are currently making polarimetric measurements on larger 2 to 4 µm particles held in an optical trap and these measurements will be discussed. We plan to investigate scatter correlations for non-spherical particles and agglomerates in the near future and will include the most recent results.