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Research on polarization of water and bubble scattering echo

As a ship passed by, a long and wide wake is left and can last for a long time. The optical characteristic of the wake is quite different from the water because of the abundant bubbles in the wake. Bubbles in the wake scatter and absorb light to alter its intensity and polarization state. As an important character of light, the polarization of scattering light of bubbles and water can be used to detect bubbles in the wake and can provide important information to the design of lidar detecting system. In this paper the theoretical and experimental study of polarization characteristic of water and bubble scattering echo are presented. The polarization of scattering light of bubbles and water were calculated by Stokes vector and Muller matrix. The echoes of water and wake bubbles simulated by ceramic tube were measured in laboratory by adjusting the angle of analyzer. The measurement results are given in the paper including the echoes of water and bubbles at different distances. The results show that by adjusting the angle of analyzer, the strong backscattering of water is compressed greatly but that of bubbles decreases a little. Take advantage of this characteristic the measurement range of detecting device can be broadened to some extent.