如果应用漫射方程分析和确定生物表面组织的光学特性，就能够确定生物活体是否发生病变，实现生物活体的无损探测。目前，光在生物体内传播常用的基本模型是半无限厚模型和两层介质模型。而实际上，人体组织为多层介质。根据漫射方程理论，在平稳状态条件下，使用外推边界条件，精确给出了匹配介质中平稳状态下三层体系光的漫射方程格林函数的解。通过此解，可以算出空间分辨漫反射。使用蒙特卡罗方法来验证三层体系的漫射方程，发现我们给出的理论解，不仅可以包括与Kienle的结论一致的两层体系模型的空间分辨漫反射的解，而且三层体系漫射方程的空间分辨漫反射解和蒙特卡罗方法基本一致。

If we can apply the diffuse equation to analyze and decide optical properties of superficial biological tissue, we can determine if the pathological changes occur in vivo, thus we can realize the noninvasive in vivo measurement. Currently, a semi-infinite media photon migration model and a two-layered turbid medium model are utilized widely. But actually, there is a multi-layered turbid medium in tissue. According to the diffusion equation, employing the extrapolated boundary condition, we analyze the diffusion of photons of a three-layered matched medium and deduce the solution of Green's function. Through comparing the spatially resolved reflectance between the solution of three-layered matched media diffusion equation and Monte-Carlo simulation, we find our solution of a three layered matched media theory not only accords with a two-layered turbid medium model which is solved by A. Kienle, but also agrees with Monte-Carlo simulation.