从上皮组织的结构特点出发,基于米氏(Mie)散射理论,建立了双层散射介质的单次后向散射光谱的理论模型,该模型通过偏振门屏蔽来自下层的噪声背景,只保留来自上层的单次散射光。计算分析了粒子的形态学参量如平均尺寸及其分布、相对折射率变化时,单次散射光谱的特征。并用傅里叶波形分析法研究了这些参量对单次后向散射光谱曲线形状及其谐波幅值的影响。结果表明,这些只经历了表层粒子单次散射的光谱信号对表层粒子的平均尺寸及其分布、相对折射率具有灵敏性。对光谱曲线波纹结构的幅值、频率,散射强度,光谱谐波的幅值有直接的影响。研究结果对早期癌症的散射光谱特征识别及其特征提取有重要的实用价值。

Theoretical model of single backscattering spectra based on Mie scattering theory is established for a two-layer scattering media according to the structure characteristic of epithelium tissue. The theoretical model makes it possible to separate the singly backscattered light from the uppermost layer by subtracting the depolarised component from the backscattered light. The characteristic of scattering spectra is analysed by simulation calculation when the morphological parameters, including mean diameter, distribution and relatine refractive index, change. The influences of mean diameter, distribution and relative refractive index of the particles of the uppermost layer on the single backscattering spectra curve and its amplitude of wave components of different orders are further studied by Fourier waveform analysis method. The results show that the single backscattering spectra are sensitive to the mean size, distribution and relative refractive index of the particles, which show direct influences on the amplitude, frequency of the ripple structure of spectra and the wave components of different orders. The simulation results can be used to identify and extract the characteristic of precancerous scattering spectra.