Confocal polarization imaging in high-numerical-aperture space.

In this work we describe theoretical and experimental physical aspects of high-resolution imaging polarimetry and its application to polarization-multiplexed encoding. We theoretically demonstrate that it is possible to resolve the orientation of two fixed dipole-like emitters placed significantly below the resolution limit if their emission is uncorrelated. Furthermore, we experimentally demonstrate this phenomenon by illuminating closely spaced asymmetric nanopits with unpolarized light and subsequently determining their individual orientation and position from the measured spatial distributions of the azimuth angle of the polarization and degree of polarization, respectively. Reduction of the optical resolution of the imaging system is also shown to only weakly affect resolution obtainable via polarization measurements.

Quantitative evaluation of skeletal muscle defects in second harmonic generation images.

Skeletal muscle pathologies cause irregularities in the normally periodic organization of the myofibrils. Objective grading of muscle morphology is necessary to assess muscle health, compare biopsies, and evaluate treatments and the evolution of disease. To facilitate such quantitation, we have developed a fast, sensitive, automatic imaging analysis software. It detects major and minor morphological changes by combining texture features and Fourier transform (FT) techniques. We apply this tool to second harmonic generation (SHG) images of muscle fibers which visualize the repeating myosin bands. Texture features are then calculated by using a Haralick gray-level cooccurrence matrix in MATLAB. Two scores are retrieved from the texture correlation plot by using FT and curve-fitting methods. The sensitivity of the technique was tested on SHG images of human adult and infant muscle biopsies and of mouse muscle samples. The scores are strongly correlated to muscle fiber condition. We named the software MARS (muscle assessment and rating scores). It is executed automatically and is highly sensitive even to subtle defects. We propose MARS as a powerful and unbiased tool to assess muscle health.

Concerted spatial-frequency and polarization-phase filtering of laser images of polycrystalline networks of blood plasma smears.

The complex technique of concerted polarization-phase and spatial-frequency filtering of blood plasma laser images is suggested. The possibility of obtaining the coordinate distributions of phases of linearly and circularly birefringent protein networks of blood plasma separately is presented. The statistical (moments of the first to fourth orders) and scale self-similar (logarithmic dependences of power spectra) structure of phase maps of different types of birefringence of blood plasma of two groups of patients--healthy people (donors) and those suffering from rectal cancer--is investigated. The diagnostically sensitive parameters of a pathological change of the birefringence of blood plasma polycrystalline networks are determined. The effectiveness of this technique for detecting change in birefringence in the smears of other biological fluids in diagnosing the appearance of cholelithiasis (bile), operative differentiation of the acute and gangrenous appendicitis (exudate), and differentiation of inflammatory diseases of joints (synovial fluid) is shown.

Mueller matrix decomposition for polarized light assessment of biological tissues.

The Mueller matrix represents the transfer function of an optical system in its interactions with polarized light and its elements relate to specific biologically or clinically relevant properties. However, when many optical polarization effects occur simultaneously, the resulting matrix elements represent several "lumped" effects, thus hindering their unique interpretation. Currently, no methods exist to extract these individual properties in turbid media. Here, we present a novel application of a Mueller matrix decomposition methodology that achieves this objective. The methodology is validated theoretically via a novel polarized-light propagation model, and experimentally in tissue simulating phantoms. The potential of the approach is explored for two specific biomedical applications: monitoring of changes in myocardial tissues following regenerative stem cell therapy, through birefringence-induced retardation of the light's linear and circular polarizations, and non-invasive blood glucose measurements through chirality-induced rotation of the light's linear polarization. Results demonstrate potential for both applications.

Avaliação em microscopia de Luz Polarizada do efeito remineralizador de materiais restauradores floretados / Evaluation by polarized light microscopy of the remineralization effet of fluoridated dental materials

Este trabalho se propôs a avaliar o efeito remineralizador dos materiais restauradores: Votrimer, Compoglass,Ketac Molar, Solitaire e TPH (controle) em lesões de cárie produzidas artificialmente. Para tanto, confeccionou-se restaurações padronizadas em blocos de esmalte bovino, bem como lesão de cárie artificial em outros espécimes, sendo estes últimos divididos em duas metades, onde uma delas não participou da ciclagem (segmento controle) e a outra foi justaposta às restaurações (segmento experimental), sendo este conjunto submetido à ciclgem de pH por um período de 28 dias. Em seguida foram obtidas lamelas de esmalte com 200um+-50um dos segmentos experimental e controle. Avaliou-se, em microscopia de luz polarizada, as alterações qualitativas e quantitativas das lesões de cárie, sendo os achados submetidos ao teste de Wilcoxon (p<0, 05) e análise descritiva. Verificou-se diferença significante (p< 0, 05) entre a profundidade das lesões de cárie submetidas ao contato com as restaurações de Ketac Molar e Compoglass. Conclui-se que o ionômero de vidro convencional e o compômero apresentaram um potencial remineralizador superior aso demais materiais estudados e que há diferença expressivas na birrefringência positiva da estrutura adamantina exposta à ação dos diferentes materiais restauradores fluoretados