For the study of the environmental characteristic parameters of typical ocean weak turbulence field, such as temperature and salinity concentration, the intensity distribution of the Gaussian beam propagation in ocean weak turbulence has been obtained by using the temperature-salinity coupling refractive power spectrum model and the theory of random phase screen, and the intensity characteristic has been analyzed by the two-dimensional gray histogram. The simulation results show that the turbulence intensity is an influence on the image characteristic, which contain the brightness and the non-uniformity degree of the image, and the effects of the variable average temperature on the image characteristics are stronger with the increase of the turbulence intensity, and then the effects of the variable average salinity concentration on the image characteristics are small under the typical weak turbulence conditions.
In this paper, we focus on the transmission characteristics of laser in propeller particle wake, the space-time simulation of particle concentration in the wake of propeller disturbance is carried out, according to the variation of particle mass concentration with time and position in laser passageway, and the transmission power model of laser in the wake of propeller particle is established, the model is validated by water-tank experiment; the deviation between theoretical model and experimental results is less than 10%. The results show that, in the region far from the propeller, there is a large scale turbulent structure, and the particle concentration varies sharply; the disturbance of propeller leads to the redistribution of particles, the concentration of particles in the flow field is no longer a stable value, but a transient value changing with time and position.
For non-cooperative target in water, it is very difficult to obtain IR characteristics of targets directly. However, we can predict the infrared features of targets through modeling and simulation method, reference for infrared detection and recognition of targets on the ocean is provided through this approach. Based on the related theory of heat transfer, in this paper, some characteristics of IR with pipe target at sea surface were researched and analyzed through analog simulation and experiment. At last, the results of the simulation and the experiment on the sea were normalized on the basis of Planck’s theorem, and the IR contrasts in different time of one day on the wave range of 8~9um were acquired, the calculation results of simulation model are in good agreement with experiment.
Bubbles in the sea are important to the research of geography, chemical engineering, biology etc. This paper presented an underwater laser imaging system for micro-bubbles, including the design, construction and performance. The system using a series 532-nm laser for lighting, and transform a piece-source. The piece-source illumination and image an area of bubbles by a high resolution CCD. It is impossible to achievement imaging the bubbles with diameters from 10µm to 500µm at the same time, we use three different focus apertures to adapt the requirements of resolution and receiver field of view. We can change the adaptive aperture for bubbles with different diameters. The imaging capability of the system is tested in the laboratory. The solid targets of specified size have been imaged in the sink, and obtained the clear images of the target with 500µm and 10µm for three magnifications. In order to verify the reliability of the system, experiments were carried out in the marine to obtain the bubble distribution in the offshore area. The results of bubbles distribution characteristics showed that the distribution is basically according with index law.
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