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Course page for Computational light scattering — Laskennallinen valonsironta 

Advanced Course, 5 credits, PAP315, Autumn 2020, Period 1

Computational light scattering assesses elastic light scattering (electromagnetic scattering) by particles of arbitrary sizes, shapes, and optical properties. Particular attention is paid to advanced computational methods for both single and multiple scattering, that is, to methods for isolated particles and extended media of particles (cf. dust particles in cometary comae and particulate media on asteroids). Theoretical foundations are described for the physics of light scattering based on the Maxwell equations and for a number of computational methods. In single scattering, the methods include, for example, the volume integral equation, discrete-dipole approximation, T-matrix or transition matrix, and finite-difference time-domain methods. In multiple scattering, the methods are typically based on Monte Carlo ray tracing. These include far-field radiative transfer and coherent backscattering methods and their extensions incorporating full-wave interactions. Students are engaged in developing numerical methods for specific scattering problems. The development and computations take place in both laptop and supercomputing environments.

Course is held virtually in Zoom, on Mondays 10-12 and Wedsnesdays 12-14. Exercise sessions are also in Zoom, on Mondays 9-10 and Wednesdays 9-10.

Lectures by Karri Muinonen, Guangland Xu, and Antti Penttilä.

Recommended preliminary knowledge: basic courses in Physics, basic courses in Mathematics, Electrodynamics, Mathematical Methods for Physicists I & II, Scientific Computing I.


Lecture material

Handouts from older courses, part 1, 2, 3, 4, 5, 6 by K. Muinonen, 7, 8, 9 by J. Markkanen, 10 by J. Herranen, 11-12 by A. Penttilä, 13, 14 by K. Muinonen


Background material

  • P. C.Y. Chang, J.G. Walker, K.I. Hopcraft. Ray tracing in absorbing media. JQSRT 96 (2005).
  • Yang, P. and Liou, K.N., 1996. Finite-difference time domain method for light scattering by small ice crystals in three-dimensional space. JOSA A13(10), pp.2072-2085.
  • Tang G, Yang P, Sun B, Panetta RL, Kattawar GW. Enhancement of the computational efficiency of the near-to-far field mapping in the finite-difference method and ray-by-ray method with the fast multi-pole plane wave expansion approach. Journal of Quantitative Spectroscopy and Radiative Transfer. 2016 Jun 1;176:70-81.
  • Mishchenko's T-matrix code for particles in random orientation, modified to read parameters from an input file: tmd-lp.flpd.ftmd.par.f. An example input file, and article explaining the parameters: 98_jqsrt_60_309.pdf
  • Example input file for Mackowski's MSTM code: mstm-input.inp
  • Example input files for RT-CB code: rayleigh-plane.inp
  • Alternative Makefile for RT-CB, copy to directory src\dsfmt under the rt-cb root folder

Suggested reading

  • J. D. Jackson: Classical Electrodynamics
  • C. F. Bohren & D. R. Huffman: Absorption and Scattering of Light by Small Particles
  • M. I. Mishchenko, J. W. Hovenier & L. D. Travis: Light Scattering by Nonspherical Particles: Theory, Measurements, and Applications
  • H. C. van de Hulst: Light Scattering by Small Particles

Previous versions of this course

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