Abstract

The possibility of using the laser optoacoustic method for studying spatial inhomogeneities of the optical properties of colloidal solutions is demonstrated. The proposed method for obtaining spatial distributions of the light extinction coefficient in the studied medium is based on the dependence of the time profile of the excited optical-acoustic signal on the absorption and light scattering coefficients in this medium. The solutions are ferromagnetic fluids based on water and kerosene with different volume concentrations of magnetite particles. The diagnostics of the optical properties of these ferromagnetic fluids has been carried out with high spatial resolution. It is shown that in a near-surface layer with a thickness of tens or hundreds of microns, the light extinction coefficient increases with the fluid depth. A nonlinear dependence of the light extinction coefficient on the liquid concentration at depths of more than 200 microns is found. The relative change in the light extinction with depth depends on the concentration of magnetite particles and the properties of the carrier liquid, as well as on the type of acoustic boundary.

中文翻译：

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激光声光方法在研究铁磁流体消光系数空间分布中的应用

摘要

证明了使用激光光声方法研究胶体溶液光学性质的空间不均匀性的可能性。所提出的用于获得被研究介质中消光系数空间分布的方法是基于激发的光声信号的时间分布对该介质中吸收系数和光散射系数的依赖性。溶液是基于水和煤油的铁磁流体，具有不同体积浓度的磁铁矿颗粒。这些铁磁流体的光学特性的诊断已在高空间分辨率下进行。结果表明，在厚度为几十或几百微米的近表层中，消光系数随流体深度的增加而增加。发现在大于200微米深度处，消光系数与液体浓度呈非线性关系。消光度随深度的相对变化取决于磁铁矿颗粒的浓度和载液的性质以及声边界的类型。