| The existing laser ship wake detection methods can not meet the need of the long-distance and high-precision detection. In the laser-guided and laser radar applications, it is found that the existence of turbulence in the atmosphere would cause the laser beam to change the direction of transmission, so that the laser spot is drift on the receiver, and that is harmful. But as viewed from informationism, the laser spot drift carry the information of the turbulent scale and intensity the laser beam conducted across.Through analyzing the ship wake patterns, it is found that the wake consists of turbulence and bubbles, so that this paper raise the wake detection method based on the laser spot drift. For the turbulence existence time longer than the bubbles', so across detecting turbulence can improve the wake detection range.Using the Mie scattering and the light scattering theory, the mechanism of the spot drift caused by the bubbles and the turbulence is analyzed respectively. With the experiment system made up of ship wake simulation setup and laser detection devices, the spot drift is investigated in the conditions of the relatively calm water, the bubbles, the turbulence and both of them in the water. Then the spot drift is measured, and the spot drift probability density distributions are calculated. The results show that in the different characteristics of the wake(calm water,bubbles,turbulence and both of them) the spot drift have different distributions, and the wake detection based on the laser spot drift is not only feasible but also possibly distinguish between the different characteristics of the wake.The wake can also affect the quality of the beam and cause the light intensity to change in spatial distribution. In order to determine the spot center and calculate the drift quickly and accurately, an algorithm determining the spot center is developed. The real-time processing program for the wake detection system based on the laser spot drift is also designed. |
PDF Full Text Request