| 摘要 |
A method and system are provided for determining the level of a body of water, whether free flowing or stationary. A rotatable reflective element is located at an area adjacent to the body of water. The reflective element is driven by a rotating motor shaft and includes a reflective surface extending 45° to the shaft axis. Rotation of the reflective surface provides scanning of a laser beam directed axially thereon. During scanning, the beam is directed at an angle to true vertical onto the surface of the body of water such that a portion of the beam is reflected from the surface. A detector array, located on the opposite side of the body of water and in a common horizontal plane with the reflective element, produces an output after receiving the reflected beam. A controller arrangement, including a counter which begins counting when-the scanned beam is vertical and which stops counting when a signal corresponding to the array output is received, determines the scan angle to true vertical. A simple calculation, based on the determined scan angle and the distance between the reflective element and the array, is then made of the distance from the common horizontal plane to the water surface so as to determine the water level.
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