Comprehensive T-Matrix Reference Database: A 2007-2009 Update

The T-matrix method is among the most versatile, efficient, and widely used theoretical techniques for the numerically exact computation of electromagnetic scattering by homogeneous and composite particles, clusters of particles, discrete random media, and particles in the vicinity of an interface separating two half-spaces with different refractive indices. This paper presents an update to the comprehensive database of T-matrix publications compiled by us previously and includes the publications that appeared since 2007. It also lists several earlier publications not included in the original database

Automated classification of single airborne particles from two-dimensional angle-resolved optical scattering (TAOS) patterns by non-linear filtering

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Comprehensive T-Matrix Reference Database: A 2012 - 2013 Update

The T-matrix method is one of the most versatile, efficient, and accurate theoretical techniques widely used for numerically exact computer calculations of electromagnetic scattering by single and composite particles, discrete random media, and particles imbedded in complex environments. This paper presents the fifth update to the comprehensive database of peer-reviewed T-matrix publications initiated by us in 2004 and includes relevant publications that have appeared since 2012. It also lists several earlier publications not incorporated in the original database, including Peter Waterman's reports from the 1960s illustrating the history of the T-matrix approach and demonstrating that John Fikioris and Peter Waterman were the true pioneers of the multi-sphere method otherwise known as the generalized Lorenz - Mie theory

Finite-difference time-domain solution of light scattering by an infinite dielectric column immersed in an absorbing medium

The two-dimensional (2-D) finite-difference time-domain (FDTD) method is applied to calculate light scattering and absorption by an arbitrarily shaped infinite column embedded in an absorbing dielectric medium. A uniaxial perfectly matched layer (UPML) absorbing boundary condition is used to truncate the computational domain. The single-scattering properties of the infinite column embedded in the absorbing medium, including scattering phase functions and extinction and absorption efficiencies, are derived by use of an area integration of the internal field. An exact solution for light scattering and absorption by a circular cylinder in an absorbing medium is used to examine the accuracy of the 2-D UPML FDTD code. With use of a cell size of 1/120 incident wavelength in the FDTD calculations, the errors in the extinction and absorption efficiencies and asymmetry factors from the 2-D UPML FDTD are generally smaller than ~0.1%. The errors in the scattering phase functions are typically smaller than ~4%. With the 2-D UPML FDTD technique, light scattering and absorption by long noncircular columns embedded in absorbing media can be accurately solved

Comprehensive Thematic T-Matrix Reference Database: A 2015-2017 Update

The T-matrix method pioneered by Peter C. Waterman is one of the most versatile and efficient numerically exact computer solvers of the time-harmonic macroscopic Maxwell equations. It is widely used for the computation of electromagnetic scattering by single and composite particles, discrete random media, periodic structures (including metamaterials), and particles in the vicinity of plane or rough interfaces separating media with different refractive indices. This paper is the eighth update to the comprehensive thematic database of peer-reviewed T-matrix publications initiated in 2004 and lists relevant publications that have appeared since 2015. It also references a small number of earlier publications overlooked previously

Phase integral of asteroids

The values of the phase integral q were determined for asteroids using a numerical integration of the brightness phase functions over a wide phase-angle range and the relations between q and the G parameter of the HG function and q and the G(1), G(2) parameters of the HG(1)G(2) function. The phase-integral values for asteroids of different geometric albedo range from 0.34 to 0.54 with an average value of 0.44. These values can be used for the determination of the Bond albedo of asteroids. Estimates for the phase-integral values using the G(1) and G(2) parameters are in very good agreement with the available observational data. We recommend using the HG(1)G(2) function for the determination of the phase integral. Comparison of the phase integrals of asteroids and planetary satellites shows that asteroids have systematically lower values of q.Peer reviewe

Finite-difference time-domain solution of light scattering by arbitrarily shaped particles and surfaces

The scattering and absorption of electromagnetic waves by irregularly shaped particles and arbitrary surfaces occur in the atmosphere, ocean, and optical devices. In this chapter, we present the finite-difference time-domain (FDTD) method [1-6] that can be used to calculate light scattering by arbitrary particles and surfaces. The FDTD technique is a numerical solution to Maxwell’s equations and is formulated by replacing temporal and spatial derivatives in Maxwell’s equations with their finite-difference equivalences. This method can be accurately applied to general electromagnetic structures including arbitrary particles and surfaces. The FDTD technique has been successfully applied to calculate light scattering and absorption by particles of different shapes in free space [5] and in absorbing medium [6]. Recently, an advanced FDTD model to calculate the interaction of electromagnetic radiation with arbitrary dielectric surfaces has been developed [7]. In the following sections, these FDTD light-scattering models are reviewed

Hubble Space Telescope Imaging Polarimetry of Comet 67P/Churyumov-Gerasimenko Obtained During the Rosetta Mission

International audienceWe present pre- and post-perihelion, high-spatial resolution (0.05 arcsec/pixel) 0.6 micron imaging polarimetry of Comet 67P/Churyumov-Gerasimenko taken with the Advanced Camera for Surveys aboard the Hubble Space Telescope (HST). The pre-perihelion observations were obtained at two epochs chosen to bracket the times when the closest orbits of Rosetta were flown (down to 10 km for extended periods: 2014-Aug-19: rh = 3.52 au, Δ = 2.76 au, α ≈ 12.0˚) and the Philae landing took place (2014-Nov-17: rh = 2.96 au, Δ = 3.43 au, α ≈ 15.7˚). Our preliminary analyses of both pre-perihelion epochs shows that the polarization position angle lies in the scattering plane, thus is negative, with a degree of polarization p% ≈ -2%. The two post-perihelion epochs were matched to the first time after perihelion that the comet was observable with HST (2015-Oct-10: rh = 1.43 au, Δ = 1.80 au, α ≈ 33.5˚), and when the comet was again viewed at small phase angle (2016-Feb-19: rh = 2.40 au, Δ = 1.49 au, α ≈ 12.0˚). We discuss our polarimetry results in context with in situ measurements of dust particles obtained with the Rosetta spacecraft