利用有限元方法对光在二维牙齿双层有限尺寸模型中传输的扩散方程进行求解，获取了光能在组织体内部的分布情况，并对牙釉质和牙本质在不同光学参量模型下的光学穿透深度进行仿真分析.结果发现，穿透深度随牙釉质散射系数的增大而减小，随牙本质的散射系数增大而增大.但牙釉质的穿透深度随散射系数的变化率(βe=0.007 97)要远远大于牙本质(βd=0.000 828).采用Monte Carlo随机统计方法验证了本文有限元求解扩散方程的正确性.

The diffusion equation describing the light transportation in two dimensional two layers dental model with finite size is solved by finite element method,and the optical intensity distribution inside the dental tissueis is obtained.The penetration depth is defined and analyzed when dental enamel and dentin is under different optical parameters.It is revealed that penetration depth decreases with the increase of scattering coefficient of dental enamel,but increases with the increase of scattering coefficient of dental dentin.In the case of variation Rate of penetration depth to scattering coefficient,dental enamel is much larger than dentin.And,the Monte Carlo random statistical method is used to verify the correct of solution of diffusion equation based on finite element method.