| 摘要 |
<p>PROBLEM TO BE SOLVED: To stably protect a light projecting means and a light receiving means from water splash and dust for a long period of time so as to make stable, continuous measurement possible by arranging optical windows and water barrier plates respectively between the light projecting means and the water surface and between the light receiving means and the water surface. SOLUTION: The general function of this device is the same as a conventional oil film detecting device. In the conventional function, however, in the case of being installed in a place with large waves or continuously operated for a long period of time, light projecting and receiving means are exposed to splashed water and polluted with water scale and dust to cause an error in polarization ratio measurement. In order to protect a laser beam source 1 and a light receiving means 6 in this device, an optical window 15 and a water barrier plate 15 are therefore installed between the laser beam source 1 and the water surface 4, and an optical window 17 and a water barrier plate 18 are installed between the light receiving means 6 and the water surface 18. The material of the optical windows 15, 17 is optical glass, and the water barrier plates 16, 18 are of double structure with small holes opened in the center of conical shape to make optical beams pass through. These water barrier plates 16, 18 shut out most of water splash and suppress the entry of dust.</p> |
