It is proposed that a macroscopic theory of propagation and scattering of light through random media can be functional for the dye liquid flowing media in the microscopic levels too, with modest approximations. Maxwell’s equation for a random refractive index medium is approximated and solved for the electric field. An analytical expression for the spectral intensity of the field scattered by the refractive index fluctuations inside a medium has been derived which was valid within the first Born approximation. Far field spectral intensity variation of the radiation propagating through the liquid medium is a consequence of variation in correlation function of the refractive index inhomogeneities. The strength of radiation scattered in a particular direction depends on the spatial correlation function of the refractive index fluctuations of the medium. An attempt is made to explain some of the experimentally observed spectral intensity variations, particularly dye emission propagation through liquid flowing medium, in the presence of thermal and flow field. 1. Introduction Scattering of light is regarded as an interaction of light with matter, which leads to a change of the direction and/or the length of the incident light wave. The incident light is deflected by collisions with particles or centers of inhomogeneity of the medium. Scattering of light occurs as an effect of heterogeneity in optical properties of the medium. Wave propagation and scattering of light through a medium are a subject of investigation that has a long history. Examination of medium by wave propagation and scattering techniques is important because it provides a tool in the study of the structure of the environment and its effects on communication through it and the detection and identification of objects in various environments. In probing the medium, we may distinguish the following two types of interactions, spectroscopic and refractive index fluctuation. In the spectroscopic interaction, the molecules in the liquid react with the wave and cause absorption and scattering of the wave. The absorption and scattering cross-sections are dependent on the properties of the specific molecule, the frequency, and the environment (density and temperature). In the macroscopic interaction, the response of the medium to the incident wave is to alter the direction and spatial coherence of the photons. Large size characteristic length of medium fluctuations provides small deflection to the incident radiation, and small size gives large scattering. The propagation of radio, acoustic, and optical
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