Airborne particle shape and size classification from spatial light scattering profiles

Kaye, Paul H.; Hirst, Edwin; Clark, James M.; Micheli, F.

doi:10.1016/0021-8502(92)90027-s

Cited by 35 publications

(16 citation statements)

References 3 publications

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“…This is not due to the aberration coma, which would lead to the squeezing or spreading of pattern features. The patterns have some similarity to those for droplets with inclusions (perhaps having inclusions larger than those for perturbed spheres) or deformed droplets [ Secker et al , 2000], multiplet particles [ Ashkin and Dziedzic , 1980; Kaye et al , 1992], fiber clusters, and flake particles [ Kaye , 1998]. Candidate particles that may produce the patterns are (1) the mixtures suggested for the perturbed sphere class but with more nonhomogeneity, (2) crystalline‐like leaf surface waxes dislodged by the wind or by rubbing motions of leaves against each other [ Rogge et al , 1993], (3) multiplet particles, (4) sea salt crystals [ Ebert et al , 2002], (5) silica shards produced by the combustion of coal [ Rietmeijer and Janeczek , 1997], and (6) crystalline particles of quartz or clay minerals [ Ebert et al , 2002].…”

Section: Analysis and Visual Classification Of The Atmospheric Taos Datamentioning

confidence: 99%

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Optical scattering patterns from single urban aerosol particles at Adelphi, Maryland, USA: A classification relating to particle morphologies

Aptowicz¹,

Pinnick²,

Hill³

et al. 2006

J. Geophys. Res.

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[1] Angularly resolved elastic light scattering patterns from individual atmospheric aerosol particles (diameter 0.5-12 micrometers) sampled during fall (October 2004) at an urban site in the Baltimore-Washington metroplex are reported. These two-dimensional angular optical scattering (TAOS) patterns were collected for polar scattering angles q varying from approximately 75°to 135°and azimuthal angles f varying from 0°to 360°. Approximately 6000 scattering patterns were sampled over a span of 18 hours from an inlet located above our laboratory roof at Adelphi, Maryland. Our instrument recorded light scattering patterns of higher resolution and accuracy than have previously been achievable. The patterns suggest that background aerosol particles have diverse morphologies ranging from single spheres to complex structures. The frequency of occurrence of particle morphologies inferred from the TAOS patterns is strongly dependent on size. For nominally 1-mm particles, 65% appear spherical (or perturbed sphere) and only about 9% have complex structure (as suggested by their complex scattering features); whereas for nominally 5-mm particles, only 5% appear spherical (or perturbed sphere) and 71% appear to have complex structure. The patterns are quantitatively characterized using a degree of symmetry (Dsym) factor, calculated by examining both mirror and rotational symmetries in each pattern. In our measurements, atmospheric particles have two distinct populations: mostly micron-sized particles with Dsym values close to that of spheres and a population of mostly supermicron particles having a low but broad range of Dsym values. These observations are consistent with the commonly accepted notion that most micron-sized particles (in the accumulation mode) appear to be nearly spherical and are probably formed in the atmosphere through gas-particle reactions; whereas most supermicron particles appear to be nonspherical and are likely directly injected into the atmosphere. Our observations suggest that Lorenz-Mie theory may be adequate for most micron-sized particles but not for supermicron particles.

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Section: Analysis and Visual Classification Of The Atmospheric Taos Datamentioning

confidence: 99%

“…The apparatus used for the measurements reported here is similar in design to an apparatus introduced by Kaye et al [1992]. In Kaye's pioneering work, a prolate ellipsoidal reflector collects light over a large solid angle (10.4 steradians) and reflects the scattered light onto a CCD detector.…”

Section: Introductionmentioning

confidence: 99%

Optical scattering patterns from single urban aerosol particles at Adelphi, Maryland, USA: A classification relating to particle morphologies

Aptowicz¹,

Pinnick²,

Hill³

et al. 2006

J. Geophys. Res.

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“…2 were recorded in the laboratory as part of a series of detailed studies into the use of spatial scattering for particle classification [9][10][11] . They were recorded using an intensified charge-couple device camera (ICCD) capable of single photon detection.…”

Section: Spatial Light Scatteringmentioning

confidence: 99%

“…For example, analysis of the spatial distribution of light scattered by each individual airborne particle passing through the measurement space of an optical scattering instrument has proved to be an effective method of improving particle discrimination e.g [9][10][11][12][13][14][15][16][17] . This is because the spatial pattern of scattered light contains information relating to the shape of the scattering particle (see Section 2).…”

Section: Introductionmentioning

confidence: 99%

An instrument for the simultaneous acquisition of size, shape, and spectral fluorescence data from single aerosol particles

et al. 2004

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We describe the construction of a bio-aerosol monitor designed to capture and record intrinsic fluorescence spectra from individual aerosol particles carried in a sample airflow and to simultaneously capture data relating to the spatial distribution of elastically scattered light from each particle. The spectral fluorescence data recorded by this PFAS (Particle Fluorescence and Shape) monitor contains information relating to the particle material content and specifically to possible biological fluorophores. The spatial scattering data from PFAS yields information relating to particle size and shape. The combination of these data can provide a means of aiding the discrimination of bio-aerosols from background or interferent aerosol particles which may have similar fluorescence properties but exhibit shapes and/or sizes not normally associated with biological particles. The radiation used both to excite particle fluorescence and generate the necessary spatially scattered light flux is provided by a novel compact UV fiber laser operating at 266nm wavelength. Particles drawn from the ambient environment traverse the laser beam in single file. Intrinsic particle fluorescence in the range 300-570nm is collected via an ellipsoidal concentrator into a concave grating spectrometer, the spectral data being recorded using a 16-anode linear array photomultiplier detector. Simultaneously, the spatial radiation pattern scattered by the particle over 5°-30° scattering angle and 360° of azimuth is recorded using a custom designed 31-pixel radial hybrid photodiode array. Data from up to ~5,000 particles per second may be acquired for analysis, usually performed by artificial neural network classification.

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“…[2][3][4][5][6][7][8][9] Since TAOS patterns vary with the composition, the TAOS technique could be used to ascertain a particle's absorption at the illuminating wavelength. This has been shown to work for electrodynamically levitated aerosols in the visible wavelength range.…”

Section: Introductionmentioning

confidence: 99%

Two-dimensional angular optical scattering patterns of aerosol particles in the mid-infrared: measurements designed to obtain particle absorption

Aptowicz

Pan

Pinnick

et al. 2004

Chemical and Biological Point Sensors for Homeland Defense

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Real-time and in-situ detection and discrimination of aerosol particles, especially bio-aerosols, continues to be an important challenge. The technique labeled TAOS (Two-dimensional Angular Optical Scattering) characterizes particles based upon the angular distribution of elastically scattered light. The detected angular distribution of light, labeled the TAOS pattern, depends upon the particle's shape, size, surface features, and its complex refractive index. Thus, the absorptive properties of a particle affect the TAOS pattern. Furthermore, we expect to use this change in the TAOS pattern, which occurs when the particle absorption band includes the input wavelength, to characterize the strength of the absorption. Thus, by illuminating a particle in the mid-infrared wavelength range, high frequency vibrational modes that are unique to the aerosol can be reached and quantified.Spherical aerosol particles (in the diameter range of 50-60 micrometers) were generated via a droplet generator and illuminated by an Interband Cascade (IC) laser designed to emit in the 3-5 micrometers wavelength range. The TAOS pattern of the elastically scattered light was detected with an InSb-focal-plane-array infrared camera.

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Airborne particle shape and size classification from spatial light scattering profiles

Cited by 35 publications

References 3 publications

Optical scattering patterns from single urban aerosol particles at Adelphi, Maryland, USA: A classification relating to particle morphologies

Optical scattering patterns from single urban aerosol particles at Adelphi, Maryland, USA: A classification relating to particle morphologies

An instrument for the simultaneous acquisition of size, shape, and spectral fluorescence data from single aerosol particles

Two-dimensional angular optical scattering patterns of aerosol particles in the mid-infrared: measurements designed to obtain particle absorption

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