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

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Liquid Phase Cloud Microphysical Property Estimates From CALIPSO Measurements

A neural-network algorithm that uses CALIPSO lidar measurements to infer droplet effective radius, extinction coefficient, liquid-water content, and droplet number concentration for water clouds is described and assessed. These results are verified against values inferred from High-Spectral-Resolution Lidar (HSRL) and Research Scanning Polarimeter (RSP) measurements made on an aircraft that flew under CALIPSO. The global cloud microphysical properties are derived from 14+ years of CALIPSO lidar measurements, and the droplet sizes are compared to corresponding values inferred from MODIS passive imagery. This new product will provide constraints to improve modeling of Earth’s water cycle and cloud-climate interactions

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

Media 1: Enhanced facial recognition for thermal imagery using polarimetric imaging

Originally published in Optics Letters on 01 July 2014 (ol-39-13-3857

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