Fundamental study on diffusing light topography

该研究项目的目的是建立嵌入在强散射介质中的吸收体的表面轮廓中的漫射光地形。首次用蒙特卡罗模拟方法研究了背向散射强度分布与光程长度分布之间的关系。在实验和模拟中，对平板、搅拌型和改进型金字塔吸波材料重建了较好的图像，从而证实了该方法的有效性。为了提高模糊图像的质量，将反卷积方法引入到边界上后向散射强度分布的形成中。通过使用蒙特卡罗模拟估计的点扩散函数来锐化模糊图像中的一部分边缘，该点扩散函数是针对放置在最浅深度的点状吸收体而估计的。最后，从光子扩散方程出发，从理论上推导了光程长度分布。得到了吸收层深度与最大光程长度之间的新关系，利用该关系重建的图像具有与模拟相同的精度。在整个研究项目中，我们确信所提出的漫射光地形图将使我们能够可视化血管图和皮下肿瘤。

The purpose of the research project is to establish a diffusing light topography in a surface profiling of an absorber embedded in a strongly scattering medium. The relation between a backscattered intensity distribution and an optical path-length distribution was first studied by means of Monte Carlo simulations. The fairly well images for a slab-plane, stir-like, and modified-pyramidal absorbers were reconstructed in experiments and simulations and, therefore, the availability of the proposed method was confirmed. The deconvolution method was introduced to the formation of the backscattered intensity distribution at the boundary to improve the quality of the blurred image. A portion of the edge in the blurred image was sharpened by using the point spread function estimated by the Monte Carlo simulation for the point-like absorber placed at the shallowest depth. Finally, the optical path-length distribution was derived theoretically from a photon diffusion equation. The new relation between the depth of the absorber and the maximum path-length was obtained, by which the image was reconstructed with the same accuracy as the simulation. Throughout this research project, we are convinced that the proposed diffusing light topography leads us to the visualization of the blood vessel map and the tumor under the skin.