In the present work, the method which allows investigating the spatial distribution of light extinction coefficient in colloidal media is experimentally realized. The proposed method is based on the dependence of temporal profiles of excited OA-signals on the absorption and extinction coefficients of the studied medium. Water-based and kerosene-based magnetic fluids with volume content of magnetite particles in the range 0.35–3.5 % were studied as an example of the medium with spatially non-uniform optical properties. The capability of the reconstruction of the one-dimensional spatial distribution for the light extinction coefficient in the investigated media is demonstrated. It was shown that the relative change of the extinction coefficient with depth depends on volume concentration of magnetite particles, type of acoustical boundary and properties of carrier liquids. In the case of acoustical rigid boundary of magnetic fluid, an additional induced anisotropy occurs, which leads to increasing of the light extinction coefficient with depth in comparison with acoustical free boundary of fluid.

中文翻译：

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用于测量消光系数的激光光声方法及其在胶体介质中的空间分布研究

在目前的工作中，可以通过实验实现研究胶体介质中消光系数的空间分布的方法。所提出的方法基于激发的 OA 信号的时间分布对所研究介质的吸收和消光系数的依赖性。作为具有空间非均匀光学特性的介质示例，研究了磁铁矿颗粒体积含量在 0.35-3.5% 范围内的水基和煤油基磁性流体。证明了重建研究介质中消光系数的一维空间分布的能力。结果表明，消光系数随深度的相对变化取决于磁铁矿颗粒的体积浓度，声学边界的类型和载液的性质。在磁性流体的声学刚性边界的情况下，会发生额外的感应各向异性，与流体的声学自由边界相比，这导致消光系数随深度增加。