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Backscattering signal from water column obtained by oceanographic Lidar is a decaying exponential function of the Lidar attenuation coefficient (Kidar). Thus Kidar can be used to derive optical properties of water. But, according to the traditional oceanographic Lidar theory, Klidar measured under single field of view (FOV) cannot be used to effectively estimate parameters of optical properties due to the deficiency of Lidar equation. However, recent studies show that multiple-scattering analysis under different FOVs is a promising way to compensate this deficiency. Therefore, an approach using an oceanographic Lidar with variable FOV has become a potential way to measure optical properties of water. In this paper, three major parts are presented. Firstly, a shipboard oceanographic Lidar system with variable FOV designed for detecting the optical property parameters of water is introduced. Secondly, on the basis of oceanographic Lidar model developed by Walker and McLean, a practical algorithm is derived to estimate the optical property parameters of water, including a (absorption coefficient), b (scattering coefficient) and Kd (diffuse attenuation coefficient). In addition, the Lidar system has be used to carry out several experiments for measuring these optical property parameters of water. Experimental analysis verifies the feasibility of measuring multiple optical properties of seawater by the Lidar with variable FOV.

Vertical profiles of sound speed in the sea can be measured by using laser excited Brillouin scattering. In this paper the dependence of the accuracy of sound speed measurement on the accuracy of the Brillouin shift measurement is analyzed. We calculated the maximum detecting depths of sound speed to an accuracy of 1 m/s by lidar with different laser pulse energy, platform altitude, telescope aperture and lidar effective attenuation coefficient. The estimation of sounding ability in the East China Sea is made in some stations. These data can be used in the design of Brillouin Lidar for the China Sea.

Ocean optics is generally considered as a branch of oceanography, but in recent years is also as a branch of the modern optics. Because of recent development of laser, optical electronics, computer and information processing, satellite remote sensing and their wide application in ocean science and exploitation, many new problems in ocean optics have been put before scientists. The specially important one is the optical information transmission in the ocean, including the narrow beam transmission of lidar in the ocean, the image transmission of underwater vision system, the data transmission of underwater laser communication, the information extraction of upwelling spectral radiance. So the ocean optics should be developed from a new point of view, i.e. the information transmission of light in the sea. This paper will discuss several problems in this aspect.