Laser forward and backward scattering characteristics and experimental study of bubbles in ship wake

The detection and tracking of ships can be realized by using the laser forward and backward scattering characteristics of ship wake bubbles. In this paper, the detection ability of two kinds of scattering to wake bubbles is studied. Based on the distribution characteristics of ship wake and bubble targets, typical bubble targets are selected to study from both micro and macro aspects. The light scattering model of water is established from the microscopic aspect, and the forward and backward scattering light intensity equations of water are derived. The circumferential scattering characteristics of a single bubble are analyzed based on the Mie scattering theory. According to the transmission characteristics of light in wake bubbles, the secondary scattering model of wake bubbles is established, and the forward and backward scattering light intensity equations are derived. In the macroscopic aspect, the laser scattering simulation model of wake bubbles is established by Monte Carlo, and the forward and backward scattering characteristics of wake bubble clusters with different radii, densities, and thicknesses are analyzed emphatically. A laser forward scattering and backscattering detection system under typical bubble characteristics was built, and the composite scattering characteristics of wake bubbles with different parameter characteristics were experimentally analyzed. The theoretical and experimental results show that with the increase of bubble radius, density, and thickness, the amplitude of laser forward scattering signal of bubble groups decreases gradually, the amplitude of backward scattering signal increases gradually, the change rate of forward and backward scattering amplitude increases, and the change rate of backscattering is obviously larger than that of forward scattering. The detection of wake bubbles by backscattering has more characteristic changes than that by forward scattering, and the detection success rate is higher. The research results can provide theoretical and experimental support for the design of a ship wake laser detection system.