AAAR 34th Annual Conference
October 12 - October 16, 2015
Hyatt Regency
Minneapolis, Minnesota, USA
Abstract View
Imaging Nonspherical Particles and Measuring their Extinction Cross Section with Digital Holography
MATTHEW BERG, Nava Subedi, Mississippi State Univeristy
Abstract Number: 177 Working Group: Instrumentation and Methods
Abstract In recent work, we have discovered an inherent link between a particle’s extinction cross section and the integral of its in-line hologram, i.e., the intensity pattern formed by the interference of the incident and scattered light. Using Mie theory, we have shown this relationship for a variety of spherical particles. The generality of the concept, however, suggests that it applies to nonspherical particles as well. In this presentation we will show that, indeed, the extinction cross section can be extracted from the holograms produced by such particles. Specifically, we investigate prolate and oblate spheroids and cubical particles in the wavelength size range. Using both the discrete dipole approximation and the T-Matrix method, when applicable, we are able to simulate the holograms and then perform a simple integration to yield the cross sections. A powerful additional ability of this technique is that an unambiguous image of the particle can be reconstructed from the exact same hologram via the Fourier transform. In an experimental context, the simplicity of the measurements involved and the technique’s high potential for application to complex-shaped coarse-mode particles will also be discussed.