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

这项研究旨在开发和应用数字全息术中的新概念，以获得空气中颗粒物的三维图像，称为粗模气溶胶(CMAS)。这些气溶胶是气候模型中辐射影响的主要不确定性来源。这项计划中的研究将使用由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。这一职业奖项中的相关教育计划将结合研究实验室环境中的实践教学和基于计划研究的在线模块的开发。总体规划的研究和教育部分寻求招收代表人数较少的少数族裔学生，并通过该大学的扩展天文学和物理多样性计划(ED-APP)提供独特的应用光学学习机会。这项研究试图建立一种新的表征范式，它摆脱了传统光散射的缺点，可以明确地描述CMA颗粒的大小和形状。光学可观测性将被自动测量，包括角散射图案、总截面和单次散射反照率。一系列数字全息实验将被用来对颗粒尺寸在1-300微米量级的CMA成像。然后将使用一种新的分析方法来量化颗粒的大小和形状分布。从这些测量的粒子全息图中，将提取对光学可观测性的准确估计。这项研究的目标是通过消除长期以来将散射测量与粒子特性联系起来的困难来解决反问题。这项研究还试图将粒子形态与光学可观测性联系起来--这在许多遥感应用中至关重要。将开发实验室全息仪器的便携式版本，用于实地研究。这里的目标是在城市和农业环境中应用相同的技术。

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.