Underwater 3D Imaging Based On Streak Tube And Date Processing

Because of the importance of ocean in the national economy and national defense, exploration of the sea becomes more and more important. Underwater laser detection technology has been widely used in the detection of fish, mines, submarines and other fields of civil and military. Non-scanning laser 3D imaging has many characteristics, such as high resolution, fast response time and high sensitivity, so it has great advantage in underwater imaging. In order to achieve three-dimensional detection of underwater targets, a laser 3D imaging system based on streak tube camera was analyzed and built, and the feasibility of the system was verified in the atmosphere.Main tasks of this paper are as follows:1、The structure, imaging principle and important characteristic parameters of streak tube are analyzed. This paper introduces the working principle and imaging characteristics of the streak tube camera, and establishes the model for calculate of depth of field in target scene.2、The design scheme of streak camera used in underwater imaging system is carried out. In order to achieve long-range underwater imaging and expand the field of imaging, at the same time, considering the effect of laser attenuation in seawater and the requirements of imaging system, the advantages and disadvantages of various types of lasers are compared.The Q-switched Nd: YAG laser which has 532 nm, narrow pulse width and high repetition rate, meet the requirements as light source which should be expanded into a sector for expending irradiation range. The system adopts accurate digital delay trigger to achieve range gated synchronization control for eliminating the influence of the low contrast and low signal to noise ratio caused by the forward scattered light and scattered light in water.3、The optical properties of seawater and the transmission characteristics of laser in underwater are analyzed,Monte Carlo method is adopted to simulate the laser underwater transmission. The model of photon underwater transmission is established, the characteristics of laser pulse broadening and transmission delay are simulated. The characteristics of time transmission and space transmission of laser in water are presented and provide the theoretical basis for the synchronization control of laser and streak camera in the nanosecond time.4、The imaging system is built. The imaging experiment of targets in the atmosphere is carried out to obtain three dimensional image data. Rationality and feasibility of the system scheme are verified. The resolution of three-dimensional imaging in different dimensions is analyzed. Influence factors of resolution in three dimensional are analyzed. The original image data are extracted by specific algorithm for three-dimensional reconstruction of the target.