Vera F. Izotova

The effect of multiple scattering in disperse media on polarization characteristics of scattered light

The effect of scattering of different multiplicity on polarization characteristics of scattered light is studied by the Monte Carlo computer simulation technique. The scattering multiplicity distribution versus the direction of scattering and dimensions of the scattering system is obtained for monodisperse systems of spherical particles of different size. The angular dependences of the elements of the light-scattering matrix (LSM) are calculated. It is shown that in a system of spherical particles, specific features of the LSM structure associated with multiple scattering have much in common with similar features of the LSM in systems of nonspherical particles under conditions of single scattering. The angular dependences of the degree of depolarization of the scattered light are studied.

Investigation of Mueller matrices of anisotropic nonhomogeneous layers in application to an optical model of the cornea

We consider a system of anisotropic layers as an optical model of the eye cornea. Effective refraction indices for normally incident light are calculated with the assumption that each layer consists of closely packed uniform cylinders (fibrils). Jones matrix formalism is used to describe light propagation through the cornea. We calculate the Jones matrices from the experimentally measured Mueller matrices. Two algorithms are used for this purpose. The experiments have shown that ~20% of cornea area studied had the structure well described by the helical model proposed.

Relationships between Mueller matrix elements of real objects

The relationships between Mueller matrix elements are considered. The correctness of their application as a criterion for consistency of experimental data and for the estimation of depolarizing ability of real objects are analyzed. Experimental errors have been assessed by means of numerical simulation.

Influence of the multiple scattering on the polarization characteristic of bio-objects

In the work, behavior of the elements of light scattering matrix (LSM) is investigated during the process of aggregation of proteins of the eye lens. We consider a system of spherical scatterers as a model of the lens. The Monte-Carlo method is used to trace migration and scattering of photons in a medium. Light scattering on the particles is described by the Mie formulas. We investigate influence of the multiple scattering on spatial and polarization characteristics of the scattered laser light accounting for the given geometry of the experiment and obtain angular dependencies of the LSM elements. Also the angular dependencies of weights of different orders of scattering are obtained. It is shown, that for small particle systems the influence of multiple scattering has a maximum for the scattering angle equal to 90 degrees. Finally, we discuss light depolarization in the lens.

Color of biotissues and artificial disperse systems under diffuse scattering of light

This paper deals with the problem of calculating the color characteristics of light scattered by disperse systems. Multiple scattering effects were taken into account.

Influence of shape and dimension of the cuvette on polarization characteristics of multiple scattered light

The Monte-Carlo method was used to study the effect of multiple light scattering on the mediums polarization characteristics. The influence of the scattering system parameters and experimental conditions on the results of LSM measurements were estimated. Calculation was performed for a monodisperse system of spherical particle. The scattering medium was enclosed in a spherical and a cylinder cells. The influence of cell wall thickness and light reflection at the medium-glass and glass-air interfaces was regarded. Various parameters of incident beam, cell diameter and scattering particles dimensions were employed for calculations.

Accuracy of polarization-sensitive optical coherence tomography of anisotropic layered biotissues

The inclusion of radiation polarization considerably extends the sensitivity and the potentials of optical coherence tomography. The recorded signals are however skewed by using wide-band light sources and polarization sensitive elements, as well as by frequency dispersion of the objects under study. It is essential for such layered system with spatial anisotropy as eye cornea and sclera.

Influence of multiple scattering on the results of measurements of light-scattering matrices

We have used, in our paper, the Monte Carlo method to study the multiple light scattering effect on the medium polarization characteristics. We have estimated the influence of a scattering system parameters and experimental conditions on the LSM measurement results. In our model a monodisperse system of spherical particle was used. The scattering substance was considered to be placed in a cylinder cell. Calculations were conducted for various parameters of incident beam, cell diameter and scattering particles dimensions. The calculations were performed for three values of particle diameters and different concentrations.

Monte Carlo simulation of polarized backscattering in spatially limited random media

Investigation of the polarization characteristics of scattered light can be effectively used for diagnosis of biotissues and bio-objects. Usually the whole indicatrices of scattered light can not be measured in vivo. So the investigation of polarized backscattered light is of great interest. The high concentration of scatterers in such objects requires the multiple scattering effects to be accounted for. In this work the Monte-Carlo method was used to describe the multiple scattering of polarized light. Trajectories of each migrating photon were traced by this method. Probability density of scattering directions are determined according to the Mie formulas with accounting for the polarization of each photon. As a result, the Stokes vectors of scattered light were calculated. So, we have determined the changes of polarization characteristics caused by the variations of the dimensions and concentrations of scatterers and by the geometry of medium. The influence of the order of scattering on the depolarization of scattered light also have been investigated. We present the patterns of spatial distribution of intensities backscattered polarized light. Calculations were performed for the systems of isotrope spherical scatterers and the obtained results were compared with the experimental data of measurement in the cross-polarized channel described in.

Dynamics of light scattering matrix in a process of scatterers aggregation

Changes of light scattering matrix elements during the aggregation process are investigated. It is shown that during the aggregation the depolarizing ability of protein solution increases for the particles smaller than wavelength and it may have a minimum for the larger ones. Light depolarization is estimated as a function of the measurement duration and of the width of particles distribution by size.