Scientific Software for Light Scattering Calculations
Dr. Adrian Doicu
- What is this software needed for ?
- Small particles exist everywhere. A few examples are dust grains permeating interplanetary and interstellar spaces, aerosol and water droplets dispersed in atmospheres, colorful metal powders shining in co 110 idal suspensions, plankton and microorganisms floating in oceans, red blood ce11s flowing in human and animal vessels and contaminating micro-particles deposited on silicon wafers. Due to its ubiquity, radiative scattering by sma11 particles of sizes comparable to the wavelength of incident radiation is a common subject for nearly a11 scientific and technical fields. These include nuclear physics, astronomy and astrophysics, atmospheric and ocean optics, biophysics, aerosol medicine, biochemistry, microbiology, radar meteorology, remote sensing, optical diagnostic techniques such as optical microscopy or optical surface scanners, photo graphie science, particle sizing, coatings technology and combustion engineering.
- Some research organizations offer electromagnetic scattering software developed in the course oftheir work. However this software is limited to specific problem areas and target audiences. The goal of the Scientific Software for Light Scattering Calculations is to cover a large class of electromagnetic scattering applications.
Which types of scattering problems can be handled by the software ?- The software package consists of several modules for computing the electromagnetic scattering by:
- axisymmetric homogeneous, isotropie or chiral particles;
- nonaxisymmetric homogeneous, isotropie or chiral particles;
- nonaxisymmetric uniaxial or biaxial anisotropie particles;
- axisymmetric layered particles;
- axisymmetric composite particles;
- axisymmetric particles with a nonaxisymmetric inclusion;
- spherical particles with a spherical inclusion;
- axisymmetric particles with multiple spherical inclusions;
- clusters of nonaxisymmetric particles;
- two-sphere clusters;
- aggregates of spheres;
- multilayered spheres;
- axisymmetric or nonaxisymmetric particles on or near a plane substrate.
- Representation of Particle Shape
- The code can handle particle with analytic representation of the surface or particles with discretized shapes. The program is flexible in the sense that complex scatterers such as clusters of different particle types (for example, axsymmetric layered, nonaxisymmetric chiral and nonaxisymmetric anisotropie particles) or particles with a cluster inhomogeneity can be computed.
Possible Types of Incident Radiaton:- The scattering characteristics can be computed for:
- plane wave incidence;
- Gaussian beam illumination;
- dipole excitation.
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Which Output Parameters Can be Calculated ?
- The output parameters depend on the particle characteritics.
- For particles and collection of particles in a fixed orientation one computes:
- the differential scattering cross section;
- the extinction, scattering and absorption cross sections;
- the amplitude, phase and extinction matrices.
- For particles or collection of particles in random orientations the output parameters are:
- the orientation-averaged differential scattering cross seetion;
- the orientation-averaged extinction and scattering cross sections;
- the orientation-averaged scattering matrix.
- For homogeneous polydisperse spheres the output information consists of:
- the ensemble-averaged differential scattering cross section;
- the ensemble-averaged extinction and scattering cross sections;
- the ensemble-averaged scattering matrix.
- Additional scattering characteritics such as polarization, backscattering and asymmetry parameter are also included in the code.
- For particles and collection of particles in a fixed orientation one computes: