Extracting Scattering Observables From Digital Holograms: Application to Aerosol Particle Characterization
Abstract
Major Goals: In short, this project addresses the inverse problem in electromagnetic scattering, and the work conducted constitutes a form of its "solution." Using digital holography, the goals of this project are to complete several experiments intended to image micron-sized aerosol particles in situ while also measuring scattering observables, including the scattering pattern, extinction cross section, and the Stokes parameters around the backward direction. The imaging aspect of this work could have substantial value as a front-end discriminator on single-particle analyzers, which is a highly desirable capability for WMD/BW detection. More broadly, the ability to unambiguously correlate a particle's image with, e.g., its scattering pattern, is the first of its kind and will enable the validation and improvement of existing scattering-only methods developed by others in this field. The specific goals are as follows: 1) Single-particle extinction measurement: The first phase of work involves demonstrating that the single-particle extinction cross section, Cext, can be extracted from a measured digital contrast hologram. The work begins with spherical calibration-particles where the extracted Cext can be directly compared to Mie theory. Once thisvalidation step is completed, the study is extended to particles of increasingly more complex morphology. 2) Scattering pattern extraction: A concept proposed to extract far-field scattering patterns is tested. The effort will begin with spherical calibration particles to enable direct comparison of the patterns to Mie theory for validation purposes. Next is an effort to perform the pattern extraction on complex shaped particles and compare to studies in the literature where, e.g., forward-scattering measurements have attempted to size such particles.
Document Details
- Document Type
- Technical Report
- Publication Date
- Nov 30, 2018
- Accession Number
- AD1080912
Entities
People
- Matthew J. Berg
Organizations
- Kansas State University
- Mississippi State University