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In this paper, a light scattering model for Total Internal Reflection Microscopy (TIRM) is described. The model handles the scattering by an axisymmetric particle of arbitrary orientation situated in the evanescent field near a plane surface, and the imaging of the scattered light via microscope optics. The scattering problem is solved by using the -matrix method and the rotation addition theorem for spherical vector wave functions, while the image of the scattered field is computed by using the Debye diffraction integral. The numerical simulations provide evidence of two working regimes for TIRM: the first regime, corresponding to an incident angle less than the critical angle of total internal reflection, provides information on the size and the orientation of the particle, while the second regime, corresponding to an incident angle larger than the critical angle of total internal reflection, is recommended for measuring the distance between the particle and plane surface. [ABSTRACT FROM AUTHOR]

The T-matrix method, which is also known as the null field method (NFM) or extended boundary condition method (EBCM), has established itself as a well known and highly regarded method for calculating light scattering by non-spherical particles. Its biggest advantage is the possibility to obtain all information about the scattering characteristics of the particle and to store it into one matrix. This enables one to do additional investigations with low efforts. Unfortunately the standard NFM fails to converge for particles with extremely non-spherical particle shapes, like long cylinders or coin-like flat cylinders. In this paper we investigate light scattering by finite particles in the form of an oblate disc sphere, which can be described as flat cylinders with a rounded edge. We use an advanced form of the T-matrix method—the null field method with discrete sources (NFM-DS). By presenting light scattering results we would like to demonstrate the potential this advanced NFM-DS offers. It allows one to calculate particle shapes with aspect ratios (relation between radius and thickness of the particle) up to 100:1 and size parameters (relation between radius and wavelength) up to 30. [ABSTRACT FROM AUTHOR]

Ferroelastic lead phosphate-type (LP) crystals undergo a sequence of phase transition $\bm{R\bar{\hbox{\bi 3}}m - C\hbox{\bi 2}/c}$ and $\bm{R\bar{\hbox{\bi 3}}m - P\hbox{\bi 2}_{\sb{\bi 1}}/c}$ [1]. The ferroic domain pattern depends on the spontaneous strain which can be diluted by the chemical composition. Light scattering from ferroelastic materials and its computer model was presented by T-matrix method at the structural phase transition. We discussed numerical procedure of T-matrix method and improved new computer program to calculate the scattering properties for domain structure of LP-type ferroelastic materials. Then, we report results of these calculations for polydispersive, randomly oriented spheroid with a refractive index, different semi-axis ratios and different size parameters. The calculation results are very close to our previous study of light scattering by spherical, cylindrical structures and convex particles. [ABSTRACT FROM AUTHOR]

A computer model of light scattering from the domain structure of Pb 3 MgNb 3 O 9 (PMN) was obtained by the T-matrix method. First we discuss numerical aspects of T-matrix computations specific for ellipsoids and present results of benchmark computations for a simple ellipsoid model. Then we report results of extensive computations for poly-disperse, randomly oriented ellipsoids with the refractive index of PMN [2.15 + ki, ( k = 0.01, 0.008, 0.015)] semi-axis ratios of 1/2, 1/1.5, 1/3, 1/4 and effective size parameters ranging from 0 to 15. These computations parallel to our previous study of light scattering by poly-disperse, randomly oriented spheroids are used to compare scattering properties of two classes of particles. [ABSTRACT FROM AUTHOR]