LED mini lidar has been developed and installed into the sea wave dynamics visualization. This study aims mini-lidar installation to small fishing ship and pleasure boat. In the viewpoints of its safety and robustness of the installed system, LED pulse beam was selected as the lidar light source. Its shallow angle observation visualizes the sea wave motion from just a front of the ship to 300m ahead. At the coast experiment, two types of LED mini lidars were used for polarization measurement and Raman scattering measurement. They were almost the same optical characteristics except for their LED wavelength, that is, 365nm for polarization lidar and 365nm for Raman lidar. To visualize the sea wave dynamics, the summation time was shortened to 0.2s. The shallow angle (depression angle) of the lidar observation was set in 2 – 10 degrees against the horizontal direction. The fundamental information of sea wave, which were wave speed, height, period and wavelength, was deduced from the lidar echo. The polarization echo measurement revealed its dependency due to the LED beam incident angle against the sea surface. The Raman echo measurement visualized the correlation between the surface atmosphere activity and the sea wave dynamics. The surface atmosphere activity on water vapor Raman echo related to the sea wave motion from the fluorescent backscattered light of sea water, while it had its original change. These results are valid for safe cruise of small boat. This additional sea wave activity information will be effective for low fuel consumption operation and the automatic control in safety cruise. They are also of interest in physical oceanography.
|