Research On Degradation Mechanism Of Underwater Optical Image Quality

Compared with acoustic,electromagnetic and other detected methods,underwater optical imaging detection has many advantages such as high resolution and large amount of information.Therefore,there are great development prospects and research significance in the fields of underwater target detection,underwater search and rescue and so on.Affected by the scattering and absorption of water,underwater imaging will suffer from quality degradation such as shortened working distance,reduced resolution,and reduced contrast,which greatly limits its application.Among them,the absorption of the water body mainly leads to the color reproduction of the underwater image,and has little effect on the clarity and resolution of the image.The scattering effect will lead to the decline of the clarity and resolution of underwater imaging,and seriously affect the detected effect of the target.Therefore,it is a technical difficulty that needs to be focused on and breakthroughs in underwater imaging.Based on the national key research and development plan-"full-sea deep video acquisition,transmission,processing technology research and development and system integration and demonstrated application",the degradation mechanism of underwater optical imaging is studied on this dissertation.Through in-depth study of the model that forward scattering affects the resolution of underwater imaging,and the construction of a corresponding experimental system to verify the model,it is mainly divided into the following aspects:1.Aiming at the quality degradation problem of underwater imaging process,the influencing factors of underwater imaging resolution have been analyzed,and the mathematical model between the water body forward scattering and underwater imaging resolution has been constructed.The degradation of the modulation transfer function under different water quality conditions and imaging distances has been numerically simulated.2.Aiming at the problem that the imaging resolution of underwater cameras is difficult to detect in actual use,an underwater imaging resolution detection system based on underwater collimator has been proposed.And the design,processing,assembly and testing of the collimator have also been completed.The underwater collimator has been used to complete the detection of the imaging resolution of the laboratory self-developed underwater camera.3.Based on the collimator,an experimental platform for the forward scattering degradation analysis have been built.The imaging resolution under different water quality and imaging distance have been quantitatively analyzed and compared with the numerical simulation results.The results show that within twice the decay length,the absolute error between the simulation and the experimental resolution is less than 5lp/mm,which proves the validity and accuracy of the numerical simulation results.