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1

Polarized phase functions in oil-in-water emulsion

Otremba Z., Piskozub J.

Optica Applicata

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2009

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Vol. 39, nr 1

129-133

EN

Results of modeling of polarized phase functions (PPFs) in water polluted by oil-in-water emulsion are presented. The shapes of PPFs for various oil droplets size distributions and for two optically different oil types are shown for various wavelengths in the visible region. It is revealed that PPFs for two perpendicular planes are different for angles greater than 50° (with even 2-fold difference close to 90°). Shapes of PPFs depend on the type of oil and on wavelength; oil droplets size distribution plays a minor role only.

2

Correction of anisotropy coefficient in original Henyey Greenstein phase function for Monte Carlo simulations of light transport in tissue

Żołek N. S., Wojtkiewicz S., Liebert A.

Biocybernetics and Biomedical Engineering

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2008

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Vol. 28, no. 4

59-73

EN

In this paper, two different methods for calculation of polar deflection angle are compared. The scattering angle is defined by numerical inversion of cumulative distribution of the original Henyey-Greenstein phase function. Results of the Monte Carlo simulations obtained in this manner are compared with results of simulations in which the analytical inversion of the probability density for the cosine of the deflection angle is applied. Investigations are carried out for media with optical properties similar to these typical for living tissues as well for very small source detector separations (50-500 [\mi]m), i.e. in conditions, in which the diffusion theory can not be applied. The distributions of visiting probability of photons penetrating into the semi-infinite medium are obtained for various methods of phase function calculation. It can be observed that the methods of calculation of polar deflection angle influence significantly spatial distributions of reflectance and visiting probability obtained by Monte Carlo simulations. The approximated transformation of the anisotropy coefficient used in simulations carried out with the use of the original Henyey-Greenstein function to effective anisotropy coefficient is presented; that makes possible comparisons of the results of Monte Carlo simulations obtained by using different methods.

3

Influence of il dispersed in seawater on the bi-directional reflectance distribution function (BRDF)

Otremba Z.

Optica Applicata

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2005

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Vol. 35, nr 1

99-109

EN

The bidirectional reflectance distribution function (BRDF) of the sea areas polluted by oil-in-water emulsion has been studied at the ends in the visible lihgt spectrum. The Monte Carlo code was applied to model water leaving radiance for the entire upper hemispere. Solar irradiance was represented by 1 billion virtual photos which reach the sea surface ar an angle of 40 deg. The results are displayed as the BRDF vs. two variables: zenith and azimuth angles. The strong impact of wavelenght on the BRDF has been revealed while, the size distribution of oil droplets has an insignificant imact. The presence of oil emulsion modifies the shape of the BRDF significantly, and the latter depends on the oil type. Irradiance reflectances and radiance reflectances derived from BRDFs obtained are also presented.

4

Phase functions of oil-in-water emulsions

Otremba Z., Piskozub J.

Optica Applicata

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2004

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Vol. 34, nr 1

93-99

EN

This paper presents the modelling of optical phase function (PF) of water polluted by dispersed oil. The shapes of PFs for various oil droplet size distributions and for two optically extremely different oil types are shown for various wavelengths from 350 to 750 nm. It is proved that changes of optical properties of oil (the complex refractive index) play minor role in PF shaping towards the impact of wavelength and size distribution. Water with oil emulsion has a PF significantly different from that of natural ocean water or harbour turbid water.