Systematic studies of light scattering 1: Particle shape

Schuerman, D. W.; Wang, R. T.; Gustafson, B. Å. S.; Schaefer, R. W.

doi:10.1364/ao.20.004039

Cited by 62 publications

(12 citation statements)

References 8 publications

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“…For the light scattering of an object, its irradiance distribution function consists of two parts, being an intensity factor and an angular function. While the intensity factor is described to be a function of the square of the projected area of the particle (A 2 ) [9], the angular function changes with particle shape [10,11]. The scattered light energy generated by the diffraction process traditionally falls on a set of static concentric detectors.…”

Section: Introductionmentioning

confidence: 99%

Particle shape and orientation in laser diffraction and static image analysis size distribution analysis of micrometer sized rectangular particles

Tinke¹,

Carnicer

Govoreanu³

et al. 2008

Powder Technology

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A systematic study has been described on the laser diffraction (LD) and static image analysis (SIA) of rectangular particles [1]. To rule out powder sampling, sample dispersion and particle orientation as a possible root cause for differences in size distribution profile, powder samples were initially immobilized by means of a dry disperser onto a glass plate. For a defined region of the glass plate the diffraction pattern as induced by the dispersed particles, and the 2D dimensions of the individual particles were measured by LD and optical microscopy, respectively. Correlation between LD and SIA could be demonstrated considering the scattering intensity of the individual particles as the most dominating factor. For both spherical and rectangular particles, theory explains the latter to relate to the square of their projected area. In traditional LD, the size distribution profile is dominated by the maximum projected area of the particles (A), and the diffraction diameters of a rectangular particle with length L and breadth B are perceived by the LD instrument to correspond by approximation with spheres having a diameter of ∅ L and ∅ B , respectively. Weighting for differences in scattering intensity between spherical and Page 3 of 56 rectangular particles exlains each rectangular particle to contribute to the overall LD volume probability distribution proportional to A 2 /L and A 2 /B. Accordingly, for rectangular particles this scattering intensity weighted diffraction diameter (SIWDD) concept explains an overestimation of their shortest dimension and an underestimation of their longest dimension. For this study various samples have been analysed with the longest dimension of the particles ranging from ca. 10 to 1000 µm. For a variety of pharmaceutical powders all with a different rectangular particle size and shape, the demonstrated correlation between LD and SIA aims to facilitate the user in a better validation of LD methods based on SIA data.

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Section: Introductionmentioning

confidence: 99%

Particle shape and orientation in laser diffraction and static image analysis size distribution analysis of micrometer sized rectangular particles

Tinke¹,

Carnicer

Govoreanu³

et al. 2008

Powder Technology

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“…Especially there are no investigations of the phase function of yellow sand particles in the North-Eastern Asia to our knowledge . The scattering property of each nonspherical particle depends on its shape as shown by a number of measurements of light scattering by nonspherical particles in laboratory conditions (e.g., Holland and Gagne, 1970;Pinnick et al, 1976;Chylek et al, 1977;Zerull, 1976;Schuerman et al, 1981;Coletti, 1984). For example, the asymmetry factor can increase or decrease as compared with the equalvolume sphere, depending on the particle shape and size (Mugnai and Wiscombe, 1986).…”

Section: Introductionmentioning

confidence: 99%

Aerosol Optical Characteristics in the Yellow Sand Events Observed in May, 1982 at Nagasaki-Part II Models

Nakajima

Tanaka

Yamano

et al. 1989

Journal of the Meteorological Society of Japan

169

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Phase functions of yellow sand particles were measured by a polar nephelometer during 24 April-11 May, 1982 at Nagasaki, Japan. They suggested a strong nonsphericity of the particles, which can be reconstructed by the semi-empirical theory of Pollack and Cuzzi or by Mie particles with large fictitious absorption. Spectral extinction cross section, single scattering albedo, asymmetry factor and backscattering phase function were estimated using the volume spectra retrieved from data of several instruments including the polar nephelometer data. Volume loading of yellow sand particles at the observation site was estimated as 666l/km2 at the maximum stage of the yellow sand event of 4-6 May and 183l/km2 for the secondary maximum of 8 May. Using two estimates of the absorption index (0.01 and a model variable with wavelengths), these values show that solar radiative heating from 0.08 to 0.4*/day can be expected in the atmosphere over considerably wide area in one yellow sand event.

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“…Also, the crystal position oscillated at a low frequency. The microwave method has been carried out by means of analog experiments by a number of researchers: Zerull et al (1993) studied interstellar dust particle shapes; Hage et al (1991) investigated cubic shapes; Schuerman et al (1981) and Lind et al (1965) examined various ellipsoids; and Greenberg et al (1960) studied cylinders. Moreover, Fuller et al (1994) measured the scattering properties of a hexagonal crystal in the microwave region.…”

Section: Introductionmentioning

confidence: 99%

An Analog Light Scattering Experiment of Hexagonal Icelike Particles. Part I: Experimental Apparatus and Test Measurements

Barkey¹,

Liou²,

Gellerman³

et al. 1999

J. Atmos. Sci.

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An experimental apparatus to measure the scattering properties of hexagonal icelike particles in the analog manner at the helium neon laser wavelength of 0.633 m has been designed and built. The instrument consists of an array of 36 highly sensitive and linear photodiode detectors that are positioned to measure the light between the scattering angles of 2.8Њ and 177.2Њ in approximately 2.5Њ increments and at any desired azimuthal angle. This array is calibrated such that the retrieved light signals are corrected to the actual light seen by the detectors to within approximately 6% at all applicable scattering and azimuthal angles. A system of electro-mechanical positioners places the sample at the desired and known position. A glass sphere and a glass fiber configured to scatter light like an infinite cylinder was used to test the operational effectiveness and calibration of the experimental apparatus. The phase functions for the parallel and perpendicular components determined from the experimental results match closely with the results computed from Mie theory.

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Systematic studies of light scattering 1: Particle shape

Cited by 62 publications

References 8 publications

Particle shape and orientation in laser diffraction and static image analysis size distribution analysis of micrometer sized rectangular particles

Particle shape and orientation in laser diffraction and static image analysis size distribution analysis of micrometer sized rectangular particles

Aerosol Optical Characteristics in the Yellow Sand Events Observed in May, 1982 at Nagasaki-Part II Models

An Analog Light Scattering Experiment of Hexagonal Icelike Particles. Part I: Experimental Apparatus and Test Measurements

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