We have developed a new third-order approximation model of Mueller matrix for spatial characterization of the
polarization effects in backscattering from highly scattering media. Using the Stokes-Mueller formalism and scattering
amplitudes calculated with Mie theory, we are able to numerically determined matrix elements. Specific features of the
2D Mueller matrix components corresponding to light backscattered from polystyrene micosphere suspensions are
characterized and compared with the experimental data for different size of scatterers, the scattering coefficient and the
anisotropy factor <i>g</i>. The results show good agreement in both azimuthal and radial direction.
The polarization properties of light backscattered from the Intralipid suspensions are investigated for different input
polarized light. The Stokes vector of the diffuse backscattered light exiting the sample is measured by use of CCD
experimental setup. The backscattering intensity and the degree of polarization are calculated from each Stokes vector.
Especially, the emphasis is on the influence of linearly polarized light with different input azimuth angle, the circularly
polarized light with the different rotary direction on the backscattering intensity and the degree of polarization of the
turbid media. Furthermore, both the relations of the backscattering intensity with the media concentration and the degree
of polarization with the media concentration for different input polarization state, different input azimuth angle are
presented. These experimental results have shown that the degree of polarization and the intensity of light backscattered
from a turbid media are sensitive to the input polarization state and the media concentration.
Polarized light scattering spectroscopy (LSS) is sensitive to the cell nuclear morphological changes in the various forms of epithelial dysplasia. Extensive studies illustrate it is a promising <i>in situ</i> technique to detect precancerous and early cancerous changes in the epithelial tissue. To determine the density and size distribution of cell nuclei with spectra, generally, Mie theory-based inverse model is adopted. This model is of multiple parameters, multiple extreme values and nonlinear. The determination of all unknown parameters needs to solve a nonlinear inverse problem. Other than least-square fitting used by previous studies, in this paper, we developed a novel method - float genetic algorithm (FGA) to determine the particle size distribution and refractive index for LSS. Our results showed that, relative errors of three estimated statistical quantities: diameter, standard deviation and refractive index are less than 5% for different additive Gauss noise levels with 70 iteration epochs. The errors gradually decrease with iteration epoch increases. Moreover, comparing with Newton-type iteration method coupled with a Marquardt-Tikhanov regularization scheme, FGA avoids the problems of local extreme value and selection of initial value and regularization parameters, thus obtains the advantages of high precision, stability and robustness.
In this paper, we have developed a Monte Carlo algorithm that simulates the wavelength dependent, elastic scattering spectroscopy of the polarization light in preinvasive cancer tissue. Using stokes vector formalism and scattering amplitudes calculated with Mie theory. The simulation results show the backscattering spectroscopy is sensitive to cellular and nuclear size.
Laser speckle imaging (LSI) through a thinned skull over the somatosensory cortex was utilized to map the spatiotemporal characteristics of local cerebral flood flow (CBF) in anesthetized rats during sciatic nerve stimulation. Region-of-interest selection and Temporal clustering analysis (TCA) method was illustrated on the dataset from high-resolution optical imaging to detect the timing and location of CBF activation. Contralateral hindlimb sensory cortical microflow was activated to increase promptly in less than 1 s after the onset of 2 s electrical stimulation then evolved in different discrete regions. Individual arteries, veins and capillaries in different diameters were activated with the time going. This pattern is similar but slightly elaborated to the results obtained from laser Doppler flowmetry (LDF), functional magnetic resonance imaging (fMRI). We presented this combination to characterize the behaviors of CBF response to neuronal activity, which might possibly lead to a better understanding of neurovascular coupling and fMRI signals.
The numerical phase function calculated with Mie theory is discussed in this paper. 1) The comparison between Mie phase function and Henyey-Greenstein phase function is made. Results show that Mie phase function is of great advantage, specially, in the simulation of polarized light transport in turbid medium. 2) The equivalent phase function of phantom consisting of micro-spheres of different sizes is presented. With this discussion, the differences between numerical phase function, Henyey-Greenstein phase function, and experimental measured phase function are discussed.
Current high-performance computers and advanced image processing capabilities have made the application of three dimensional visualization objects in biomedical images facilitate the researches on biomedical engineering greatly. Trying to cooperate with the update technology using Internet, where 3-D data are typically stored and processed on powerful servers accessible by using TCP/IP, we held the results of the isosurface be applied in medical visualization generally. So in this system we use the 3-D file format VRML2.0, which is used through the Web interface for manipulating 3-D models. In this program we implemented to generate and modify triangular isosurface meshes by marching cubes algorithm, using OpenGL and MFC techniques to render the isosurface and manipulate voxel data. This software is more adequate visualization of volumetric data. The drawbacks are that 3-D image processing on personal computers is rather slow and the set of tools for 3-D visualization is limited. However, these limitations have not affected the applicability of this platform for all the tasks needed in elementary experiments in laboratory or data preprocessed. With the help of OCT and MPE scanning image system, applying these techniques to the visualization of rabbit brain, constructing data sets of hierarchical subdivisions of the cerebral information, we can establish a virtual environment on the World Wide Web for the rabbit brain research from its gross anatomy to its tissue and cellular levels of detail, providng graphical modeling and information management of both the outer and the inner space of the rabbit brain.
Multiphoton excited fluorescence detection is a powerful tool for probing chemistry and structure deep within biological tissue, for performing sensitive measurement on deep-UV (ex 200-300 nm) specimen. We present an approach for rapid analysis of Rhodamine B using multiphoton excited fluorescence detection coupled to capillary electrophoresis separations. In this highly versatile approach, Rhodamine B is excited through the nearly simultaneous absorption of two low-energy photons, fluorescence can be detected efficiently with low background. In these studies, Rhodamine B is fractionated in several minutes, with mass detection limits as low as 10 amol (2nM). This approach is demonstrated to be a powerful tool for analyzing the complex biological samples of minute quantities.
A restoration mathematics model is established for deep layer in multiphoton excitation scanning microscopy by analyzing three-dimensional confocal scanning image attenuation in turbid medium. Furthermore we build the relationship between the attenuation coefficient and scattering coefficient and restore the deep layer images dependent on the relationship. The restored images of pig epidermis in the light of this model are discussed.