This paper presents the results of experimental study of full field laser speckle imaging due to cortex microcirculation
state monitoring for laboratory rats under conditions of stroke and the introduction of agents. Three groups of
experimental animals from five animals in each group were studied. The behavior of blood flow, studied by speckle
imaging technique, matched the expected physiological response to an impact.
The results of experimental study of monitoring the microcirculation in tissue superficial layers of the internal organs at
gastro-duodenal hemorrhage with the use of laser speckles contrast analysis technique are presented. The
microcirculation monitoring was provided in the course of the laparotomy of rat abdominal cavity in the real time.
Microscopic hemodynamics was analyzed for small intestine and stomach under different conditions (normal state,
provoked ischemia, administration of vasodilative agents such as papaverine, lidocaine). The prospects and problems of
internal monitoring of micro-vascular flow in clinical conditions are discussed.
Results of the contrast analysis of time-averaged dynamic speckle patterns in application to monitoring of the structure modification of the thermally treated collagenous tissue such as cartilage are presented. The modification presumably induced by the bound to free water phase transition in the matrix of the treated tissue cause the specific feature of evolution of the time-averaged speckle contrast with the change of the current temperature of modified collagen tissue. This evolution appears as hysteresis associated with irreversible changes in tissue structure.
Study of influence of an absorption of scattering media on the residual polarization of backscattered linearly polarized light is carried out. Approximate expression describing dependence of the degree of residual linear polarization on optical properties of disordered media is obtained. Phenomenological theory of multiple scattered field formation due to superposition of partial components with different optical paths in multiply scattering medium and previously described similarity of various statistical moments of multiply scattered optical fields are used to estimate the degree of residual polarization. Suppression of partial components with large values of optical paths causes increase of this parameter for detected backscattered light. This effect is observed at the wavelengths of selective absorption of disordered media. Experimental results obtained for phantom scattering samples such as milk and in- vivo biological tissue (human skin) are presented.
The annual International school for young scientists and students on optics, laser physics and biophysics [Saratov Fall Meeting (SFM)] having five years experience in organization of a special Internet session is described. The technology of the Internet conference organizing as a new approach for distant and continuing education is discussed.
The paper gives the analysis of local polarization states of scattered speckle patterns in case of transition from low- step scattering to multiple scattering mode. Simple phenomenological approach to the description of polarization structure of speckles caused by interference of perpendicularly polarized optical fields is considered. Experimental results obtained with layered scattering slab consisting of a number of thin Teflon films are presented.
Polarization relaxation in the disordered multiply scattering media with non-zero absorption is studied. Experiments with phantom scattering media such as water suspensions of polystyrene spheres and diluted milk have been made to analyze the dependencies of polarization degree of multiply scattered light on the absorption coefficient for monodisperse and polydisperse scattering systems. The concept of optical path distribution is used for phenomenological interpretation of the obtained results. Monte-Carlo simulation is applied to obtain the distributions of the effective optical paths for given scattering and absorption conditions.
Phenomenological description of the local polarization structure of multiple scattered speckle patterns is discussed. Different approaches to these structures characterization are reviewed. Experimental results obtained with multiple scattering model objects show that statistical properties of local polarization parameters can be described by using the `quasi-scalar' approach; in this case multiple scattered speckle pattern is interpreted as the superposition of two orthogonally polarized fully developed statistically independent components.
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