A bubble in water is an example of a scatter for which the refractive index of the core (gas) is less than that of the surroundings. So bubbles in water exhibit scattering phenomena which differs significantly from those for drops in air or solid particles in water. The scattering of bubbles in water as a means to detective the size of bubble has been investigated in many ways such as Mie theory and Davis’s geometric-optics theory. In this paper, a new physics-optics method was applied to manifest the scattering properties of a spherical bubble in water. The angular distribution of intensity of light scattered from a collimated beam that is incident upon a spherical air bubble in water is determined for any bubble with radius greater than a few wavelengths of the incident light. One external reflection, four internal reflections and four refractions are considered. The intensity of scattering light is tabulated and plotted as a function of the observing angle, the effects of the bubble’s radius, the electric field’s polarization of the incidence light and the wavelength of the incidence light on the scattering intensity distribution are also discussed.
The transportation of lidar’s laser beam in seawater is simulated by Monte Carlo method, which combined with statistic, estimate method and weigh method. It should be hypothesized that the incidence laser beam is vertical down and the beam is infinitude thin and vertical. The edge of atmosphere and seawater is located as cone. The axial line of the cone is same to the axial line of the laser impulse spread. It shows that the FOV (fields of view) of lidar’s detector have some influence to the waveform of echo signals. The influence is quite clear when the fields of view is quite small. The larger of the fields of view is, the slower the attenuation speed is. The trend goes to saturation when the fields of view add to a certainty. The conclusion is that the best receiving FOV is between 50mrad ~ 70mrad to the on-board lidar system which located in height at about 500 meters.