The decay behavior of specific intensity is studied for spatial-frequency domain imaging (SFDI). It is shown using the radiative transport equation that the decay is given by a superposition of different decay modes, and the decay rates of these modes are determined by spatial frequencies and Case’s eigenvalues. This explains why SFDI can focus on shallow regions. The fact that light with nonzero spatial frequency rapidly decays makes it possible to exclusively extract optical properties of the top layer of a layered medium. We determine optical properties of the top layer of a solid phantom. This measurement is verified with different layered media of numerical phantoms.

中文翻译：

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辐射输运方程的空间频域成像衰减特性和光学参数识别

研究了特定强度的衰减行为，以进行空间频域成像（SFDI）。使用辐射输运方程显示，衰减是由不同衰减模式的叠加给出的，而这些模式的衰减率是由空间频率和Case的特征值确定的。这就解释了为什么SFDI可以专注于浅海地区。具有非零空间频率的光迅速衰减的事实使得可以专门提取层状介质顶层的光学特性。我们确定了实体模型顶层的光学特性。可以使用数字幻像的不同分层介质来验证此测量。