| During the transmission of light in a three-dimensional inhomogeneous medium,various characteristics of light waves(deflection,polarization,phase,direction,amplitude,wavelength,etc.)can reflect a large amount of information in the light transmission process.And the process of absorption,scattering,refraction,reflection,etc.of light in inhomogeneous medium will also affect the transmission of light.Therefore,it is of great significance to carry out analysis and research on multi-elements of optical transmission in three-dimensional inhomogeneous medium.In this paper,two types of typical three-dimensional inhomogeneous media,such as atmospheric shock flow field and seawater,are selected as research objects.Analytical studies were carried out on the air shock flow field and the light transmission process in an inhomogeneous seawater medium.The characteristics and changing rules of light in two kinds of inhomogeneous media have been obtained.The research results are of great value for the development of new detection and tracking technologies.Establish the light transmission model in three-dimensional non-uniform medium based on the the Runge-Kutta ray tracing method.For the optical transmission process in the atmospheric shock flow field,the optical modeling of Runge-Kutta ray tracing is used for optical modeling.The optical refractive index model of non-uniform atmospheric medium is studied and summarized under complex environments such as high temperature and high pressure.A refractive index gradient interpolation method for a three-dimensional non-uniform flow field is proposed.The feasibility and accuracy of the Runge-Kutta ray tracing model are verified by the geometrical optics theory.Research on the light deflection characteristics and schlieren imaging of the atmospheric shock wave field in a high-speed aircraft.The atmospheric shock flow field of a high-speed aircraft under typical operating conditions was obtained through Fluent software simulation.Based on the refractive index and refractive index gradient of any point in the flow field grid,the Runge-Kutta ray tracing method was used to simulate the light deflection trajectory in the flow field around the shock wave.The effects of flight Mach number,flight altitude,incident light wavelength,and initial incidence angle on the degree of light deflection were analyzed.At the same time,the grayscale imaging of the excited ripple shadow structure when a high-speed aircraft is flying in a background environment such as city,desert and ocean is completed.Research on laser transmission characteristics in heterogeneous seawater in typical area.Established a transmission model for the collision and scattering of photons and suspended particles,the absorption of water bodies,the refraction and transmission to the air/water interface,and the Lambertian reflections on the surface of the target and the surface of the target during laser transmission in seawater.The Monte Carlo method was used to simulate the spatio-temporal characteristics of laser echo signals in three types of typical seawater.The effects of different scattering times of laser photons on the total echo signals were studied.The results showed that the single scattering of the laser to the total echo The signal contributes the most.The characteristics of water in the clean sea areas of the four seas in China's offshore areas were analyzed,and the effects of different water bodies on the laser underwater detection process were compared and studied.For the large number of droplets and air bubbles in the disturbed seawater,the absorption and scattering coefficients of the droplet layer and the bubble layer were obtained according to the Mie scattering theory of single droplets and bubbles,Using the method of random generation of droplet and bubble concentration in sea water,the effects of the absorption and scattering characteristics of the droplet layer and bubble layer on the spatio-temporal characteristics of the laser backscatter signal were simulated. |
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