CAREER: In Situ Study of Aerosols in the Coarse Mode With Digital Holography

本研究旨在发展和应用数字全息术中的新概念，以获得称为“粗模式气溶胶”（CMAs）的空气中颗粒的三维图像。这些气溶胶是气候模式中辐射影响的主要不确定性来源。计划中的研究将使用PI开发的开创性数字全息设计来测量这些气溶胶的各种光学参数。该职业奖的相关教育计划将在研究实验室环境中进行实践教学，并在计划研究的基础上开发在线模块。总体规划的研究和教育部分寻求招募代表性不足的少数民族学生，并通过该大学的扩大天文学和物理学多样性计划（ED-APP）提供应用光学方面的独特学习机会。本研究旨在建立一种新的表征范式，该范式可以摆脱传统光散射的缺点，并且可以明确地描述CMA颗粒的大小和形状。光学观测数据将自动测量，包括角散射图、总截面和单散射反照率。一系列的数字全息实验将用于成像粒径为1-300微米的cma。然后将使用一种新的分析方法来量化颗粒大小和形状分布。从这些测量的粒子全息图中，将提取光学观测的准确估计。这项研究的目标是解决反问题，通过消除长期存在的困难，将散射测量与粒子特性联系起来。该研究还寻求将粒子形态与光学观测相关联——这在许多遥感应用中是至关重要的。将为实地研究开发一种便携式的实验室全息仪器。这里的目标是在城市和农业环境中应用同样的技术。

This study seeks to develop and apply new concepts in digital holography to obtain three-dimensional images of airborne particles, called "coarse mode aerosols" (CMAs). These aerosols are a major source of uncertainty for radiative impacts in climate models. The planned research will use a pioneering digital holographic design, developed by the PI, to measure various optical parameters of these aerosols. The associated education plan in this CAREER award will integrate hands-on teaching in a research lab setting and the development of online modules based on the planned research. The overall planned research and educational components seek to recruit underrepresented minority students and provide a unique learning opportunity in applied optics through the university's Expanding Diversity in Astronomy and Physics Program (ED-APP). This study seeks to establish a new characterization paradigm that is free from the drawbacks of conventional light scattering and can unambiguously describe CMA particle size and shape. Optical observables will be automatically measured, which include the angular scattering pattern, total cross sections and single scatter albedo. A series of digital holographic experiments will be used to image CMAs with particle sizes of the order of 1-300 microns. A new analysis method will then be used to quantify the particle size and shape distributions. From these measured particle holograms, accurate estimates of optical observables will be extracted. The goal of this research is to solve the inverse problem, by removing the long standing difficulty relating scattering measurements to particle properties. The study also seeks to correlate particle morphology with optical observables - of critical importance in many remote sensing applications. A portable version of the laboratory holographic instrumentation will be developed for field studies. The goal here is to apply the same techniques in urban and agricultural environments.