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• Mie scattering cross-sections can be efficiently represented by look-up tables. • Stochastic algorithm automatically discovers optimal look-up table grid points. • Single look-up table valid for a wide range of size ranges and optical constants. • Look-up table (for use in Matlab) available for download on Mendeley data. We report a novel algorithm for generating optimized look-up tables suitable for rapid evaluation of various light scattering parameters and other hard-to-evaluate functions. Our method uses a stochastic algorithm to minimize the number of look-up table points needed while achieving high accuracy and speed. As an example, we present a general Mie scattering look-up table applicable to a large range of size parameters (0.02 < x < 200) and most materials (organics, inorganics, minerals, metals etc.) with real and imaginary parts of the refractive index ranging from 0.2 to 5 and 0 to 5, respectively. The look-up table is up to 3500 times faster than evaluating the Mie analytical expressions (in Matlab). This method opens up new possibilities in detection algorithm development (e.g. large synthetic datasets for machine learning), inverse problems and all other problems where a large number of Mie scattering coefficients needs to be rapidly evaluated. Furthermore, this method is applicable to other, related scattering problems. For example, we also present look-up tables for scattering efficiencies for spheres on various substrates. [ABSTRACT FROM AUTHOR]

Abstract: Motivated by new photothermal techniques to detect trace quantities of illicit substances, we are examining the heat transfer of small particles randomly distributed on surfaces that are selectively heated by a laser beam. For an optimal choice of laser power, illumination time and other parameters, we need formulas describing how the thermal signal depends on particle size, their distribution on the substrate surface and thermo-physical properties of the materials involved. In this manuscript we compare very simple physical models and computational simulations with experimental data from polyethylene microspheres on a polished copper surface, with diameters ranging from 20 to 200μm. Heat transfer through air dominates the process, both for single particles and between particles in clusters. The influence of high particle densities per substrate area on the heat transfer process is factored into the simulation by using a cell with just one particle and symmetric boundary conditions. Further simulations where irregular-shaped carbon pieces were approximated as lying cylinders indicate that our simple model can also describe the thermal behavior of a wider class of realistic particles on solid surfaces. [Copyright &y& Elsevier]