无序介质的非相干背散射

讨论两种散射，导出相应的分布函数，运用蒙特卡罗法模拟光子在无序介质中的随机行走过程，得到非相干背散射空间分布及反射率。计算结果表明：1、散射不同，非相干背散射空间分布和反射率不同，非相干背散射反射率随光入射角增大而增大；2、非相干背散射反射率随无序介质吸收系数增大而减小，通过测量非相干背散射反射率可得吸收系数，进一步可得每次散射光子被微粒吸收的概率；3、非相干背散射反射率随光子平均自由程增大而减小，通过测量非相干背散射反射率可得平均自由程，这比检测相干背散射来得到平均自由程要容易。最后，讨论了背散射对无序激光器的影响。

Incoherent backscattering of random medium

Two kinds of scatterings are discussed and the corresponding distribution functions are deduced . The spatial distribution of incoherent backscattering and reflectivity are deduced by simulating the process of stochastic photon movement in random medium using the Monte Carlo method. The results show that different scattering have different reflectivity and spatial distribution of incoherent backscatter. As the angle of incidence increasing, the reflectivity of incoherent backscattering increases. Reflectivity of incoherent backscattering decreases as the absorption coefficient of random medium increasing. By measuring the reflectivity of incoherent backscattering, we can get first the absorption coefficient and then the probability that photon is absorbed by particle each time scattering. Reflectivity of incoherent backscattering decreases as the mean free path of photon increasing .The mean free path can be gotten by measuring the reflectivity of incoherent backscattering , it is easier than testing coherent backscattering to get the mean free path. Lastly, the effect of backscattering on random laser is discussed.