Time-resolved imaging of settling mineral dust aerosols with digital holography

Gaudfrin, Florian; Santos, Eduardo T. F.; Presley, DeAnn; Berg, Matthew J.

doi:10.1364/osac.404104

Cited by 4 publications

(2 citation statements)

References 18 publications

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“…Such information can be extracted through conventional holographic reconstruction algorithms (e.g., Fraunhofer, Fresnel‐Kirchhoff, or Rayleigh‐Sommerfeld) or machine learning based on algorithms introduced recently by Shao, Mallery, and Hong (2020) and Shao, Mallery, Kumar, and Hong (2020). DIH has been widely applied for measuring mineral dust particles (Gaudfrin et al., 2020), cloud particles (e.g., cloud droplets, ice crystals; Fugal et al., 2004; Larsen et al., 2018), microorganisms (e.g., plankton Guo et al., 2021, and microcystis aeruginosa You et al., 2020), and drosophila (Kumar et al., 2016). Field measurements of snow particles with a large range of sizes and shapes using DIH have also been successfully conducted with a simple and low‐cost setup (C. Li et al., 2021a; J. Li et al., 2021b; Nemes et al., 2017).…”

Section: Introductionmentioning

confidence: 99%

Snow Particle Analyzer for Simultaneous Measurements of Snow Density and Morphology

Li,

Guala,

Hong

2023

JGR Atmospheres

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The detailed characterization of snow particles is critical for understanding the snow settling behavior and modeling the ground snow accumulation for various applications such as prevention of avalanches and snowmelt‐caused floods, etc. In this study, we present a snow particle analyzer for simultaneous measurements of various properties of fresh falling snow, including their size, shape, type, and density. The analyzer consists of a digital inline holography module for imaging falling snow particles in a sample volume of 88 cm3 and a high‐precision scale to measure the weight of the same particles in a synchronized fashion. The holographic images are processed in real‐time using a machine learning model and post‐processing to determine snow particle size, shape, and type. Such information is used to obtain the estimated volume, which is subsequently correlated with the weight of snow particles to estimate their density. The performance of the analyzer is assessed using monodispersed spherical glass and foam beads, irregular salt crystals, and thin disks with various shapes with known density, which shows <10% density measurement errors. In addition, the analyzer was tested in a number of field deployments under different snow and wind conditions. The system is able to achieve measurements of various snow properties at single particle resolution and statistical robustness. The analyzer was also deployed for four hours of operation during a snow event with changing snow and wind conditions, demonstrating its potential for long‐term and real‐time monitoring of the time‐varying snow properties in the field.

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Section: Introductionmentioning

confidence: 99%

Snow Particle Analyzer for Simultaneous Measurements of Snow Density and Morphology

Li,

Guala,

Hong

2023

JGR Atmospheres

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“…As such, DHM is difficult to apply to aerosols in an in situ way since the motion of free-flowing particles is difficult to control; lens-free DIH is then the simplest approach to take. A number of examples illustrate the usefulness of DIH for aerosol characterization in the laboratory 30 – 38 , industrial settings 39 , the outdoor environment 40 , 41 , from research aircraft 42 – 44 , and from a small unmanned areal vehicle 45 .…”

Section: Introductionmentioning

confidence: 99%

The color of aerosol particles

Giri

Berg

2023

Sci Rep

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Digital in-line holography (DIH) is an established method to image small particles in a manner where image reconstruction is performed computationally post-measurement. This ability renders it ideal for aerosol characterization, where particle collection or confinement is often difficult, if not impossible. Conventional DIH provides a gray-scale image akin to a particle’s silhouette, and while it gives the particle size and shape, there is little information about the particle material. Based on the recognition that the spectral reflectance of a surface is partly determined by the material, we demonstrate a method to image free-flowing particles with DIH in color with the eventual aim to differentiate materials based on the observed color. Holograms formed by the weak backscattered light from individual particles illuminated by red, green, and blue lasers are recorded by a color sensor. Images are reconstructed from the holograms and then layered to form a color image, the color content of which is quantified by chromaticity analysis to establish a representative signature. A variety of mineral dust aerosols are studied where the different signatures suggest the possibility to differentiate particle material. The ability of the method to resolve the inhomogeneous composition within a single particle in some cases is shown as well.

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Tutorial: Aerosol characterization with digital in-line holography

Berg

2022

Journal of Aerosol Science

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Time-resolved imaging of settling mineral dust aerosols with digital holography

Cited by 4 publications

References 18 publications

Snow Particle Analyzer for Simultaneous Measurements of Snow Density and Morphology

Snow Particle Analyzer for Simultaneous Measurements of Snow Density and Morphology

The color of aerosol particles

Tutorial: Aerosol characterization with digital in-line holography

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