| The diffuse reflectance measured at microdomains close to the source is sensitive to phase-function-dependent parameter ? which is related to tissue micro structure.A diffuse reflectance model with a samll receiving aperture was studied,and a method of measuring ? by a optical fiber probe was presented and the experimental verification was carried out by bioloical tissue phantoms of Intralipid.Based on spherical fractal model of Intralip id,the function relationship between diffuse reflectance and ? was established using Monte Carlo method.Research shows that the diffuse reflectance is linearly related to the dimensionless reduced scattering coefficient us'?(? is selecting aperture)and its slope is a quadratic function of?.The experimental results show that Intralipid s ??2.04,fractal dimension?=2.93 and anisotropy factor g=0.816,these values are in good agreement with the literature,so the feasibility of the method of measuring y is verified.The main work includes the following:1.In this paper,biological tissue phantoms of Intralipid is used to verify the light scattering from the light source which is related to the micro structure information.According to the spherical fractal structure of Intralipid,the Mie theory is used to calculate the scattering phase function of the fractal dimension as different values,and the linear relation between the parameter ? and the fractal dimension ?is found.2.The influence of microstructure parameter y and collecting aperture ? on diffuse reflectance is analyzed,quantitative analysis is carried out,and the empirical analytical model R?(?s'?,?eff)is obtained.It is found that the reflectance has a linear relationship with the dimensionless reductive scattering coefficient ?s;?,and its ratio coefficient is the micro structure parameters ?,which has the advantages of simple mathematical form compared with other subjects.3.Intralipid is a commonly used biological tissue phantoms,and its optical properties have many derivation,but the microstructure parameters of the tissue have not been reported by the experimental results.Based on the spherical fractal structure characteristics of Intralipid,the scattering phase function is calculated by Mie theory.The relationship between reflectivity and parameter ? is obtained by using MC method,and the ? of Intralipid is obtained by using this formula,which is found to be consistent with the theoretical calculation value.The ? Intralipid is measured by experiment,and a measuring nethod of ? is put forward.The experimental results are in good agreement with those reported in the literature.4.A double layer optical fiber probe is designed,which can realize small aperture measurement and is of great significance for minimally invasive or noninvasive measurement in vivo. |
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