Quantitatively Characterizing The Anisotropic Microstructure Using The Mueller Matrix Decomposition Technique

Polarization imaging technology shows great application potentialsin thefield of biomedical research. The polarization characteristics of scattered lightin biological tissue contain rich structural information. Thus, developing aproper polarization tissue optics model, investigatingthe polarized lightpropagation in the scattering media and characterizing thepolarizationpropertiesare essential for the applications of polarization imagingtechniques in clinical biomedical diagnosis.In this thesis, we presented a sphere-cylinder birefringence model (SCBM)for anisotropic samples such as biological tissues, and preparation of theexperimental phantom of the model.In the phantom, the polystyrene spheresand fibers were used to represent the isotropic and anisotropic scatterers, thebirefringence value was adjustedby stretching the polyacrylamide cubetoproduce a linear birefringence linearly proportional to the stretched length. Byregulating the variety of scattering and propagation parameters in the phantom,the properties of different biological tissues can be simulated. We also set upexperiments to measurethe forward scattering Mueller matrices. Bothexperimental results and Monte Carlo simulations on SCBM have proven thatsuch a polarized model is capable of producing the optical scattering featuresfor different biological tissues.In this thesis, we used the Mueller matrix decomposition method toextract a number of parameters, which can be proved to be related to thephysical process of scattering. We summarized the relationship between theMueller matrix decomposition parameters andthe microstructural changes ofthe SCBM. Both the experimental and Monte Carlo simulated results haveshown that,the Mueller matrix decomposition parameters have differentfeedbacks with the variationsof the shapes of scatterers, the scatteringcoefficients and the proportion of scatterersin the media. These changes can beused to obtain the microstructral information of the scatterers and surroundingmedium for the samples. Furthermore, these changes can be related with pathological changes. Through this work, we established therelationshipbetween Mueller matrix decomposition parameters and microstructuralchanges of the SCBM.In many real biological tissues, the birefringence on the fibers can not beignored. Therefore, weexpended the sphere-cylinder birefringence modelfurther to include the intrinsic birefringence on the cylindrical scatterers. Wealso developed a new Monte Carlo simulation program to calculate the effectsdue towell-orderedbirefringent fibersto mimic biological tissues. Thesimulated results testified that theretardance increases linearly with intrinsicbirefringence on the cylinders and almost linearly with the diameter of thebirefringent cylinder. Compared with the SCBM, the cylinder-birefringencemodel shows quite a different characterisctic feature. Furthermore, weinvestigated the interaction and the equivalent between anisotropic scatterersand the birefringent media.Based on the above tissue optics models and Mueller matrixdecomposition method, we also studied the forward scattering Mueller matrixdecomposition parameters for characterizing the properties of three kinds ofcancerous tissue sections.The microstructures and polarization properties ofthese cancer samples are different. Experimental results of biological tissuesshow that the Mueller matrix decomposition parameters can be used aspotentially powerful tools for biomedical diagnosis purposes.