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Light propagation in tissues: the role of polarization

English title Light propagation in tissues: the role of polarization
Applicant Ricka Jaroslav
Number 103730
Funding scheme Project funding (Div. I-III)
Research institution Institut für angewandte Physik Universität Bern
Institution of higher education University of Berne - BE
Main discipline Other disciplines of Physics
Start/End 01.04.2004 - 31.10.2006
Approved amount 137'210.00
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Keywords (7)

MULTIPLE SCATTERING; LIGHT PROPAGATION; POLARIZATION; BIOMEDICAL PHOTONICS; biological tissues; Monte Carlo; simulations

Lay Summary (English)

Lead
Lay summary
With the present project we seek to improve our understanding of the roleof the polarization in light propagation through biological tissues. Theaim is to provide the tools and the know-how needed for the developmentof novel diagnostic techniques.

The most conspicuous optical feature of the tissue is its turbidity: lightmay penetrate deep into the tissue (in the near infrared window) butpropagates in a highly irregular fashion. The basic features of lightpropagation in turbid media can be understood in terms of an amazinglysimple model: one envisions photons as randomly bouncing billiard balls.However, this classical model is completely incoherent, the onlyremainder of the wave nature of the light is the probability distributionof the flight step orientation (so-called phase function), andpolarization is completely neglected. In the recent years, however, theimportance of polarization has been recognized and the research in thisarea intensified. On one hand, the increase of research activities ismotivated by the need to improve the resolution of imaging through turbidmedia. On the other hand, one can also hope for new diagnostic techniques,based on the detection of birefringence or chirality. This research couldeventually lead to development of a reliable technique for non-invasiveglucose monitoring, improving the quality of life of milions of diabetespatients.

The products of the first stage of the project will be advanced generalpurpose modeling tools:
i) A mathematical modeling tool, i.e., Monte Carlo simulation softwarewhich incorporates the evolution of the polarization state and allows tochose the properties of the background medium and of the singlescattering processes, including the dynamic correlations.
ii) A physical modeling tool, i.e., a tissue phantom that allows to changethe optical properties in a controlled fashion and that mimics the tissueas closely as possible, including the dynamics.

With these tools at hand we shall tackle specific questions, such a forexample:
How does the selection of the polarization state influence the pathlengths distributions and the special sensitivity profiles? Whatinformation can be obtained by combining the polarization analysis withdynamic correlation techniques? In particular, how does the birefringenceor chirality influence the cross-correlation between the twopolarization states?
Direct link to Lay Summary Last update: 21.02.2013

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