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28 September 2011 Optical liquid-level sensor using a collimator in a pipe with small holes
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To measure a level of a flammable liquid, optical sensing methods have been reported more effective than other methods based on mechanical and electrical methods. This paper reports a new method that uses a collimator and a pipe to measure the liquid level. The presented liquid-level sensor consists of a gradient-index lens (GRIN lens), a metal pipe with small holes, and a floating buoy as a mirror. The liquid in the tank flows into the pipe through small holes and the floating buoy coated with aluminum will float over the liquid. The light collimated by a GRIN lens will be reflected at the floating buoy, which operates like mirror. The light reflected from the mirror is refocused through the GRIN lens and is varied as a function of the liquid distance. It is a simple design using a pipe to collect easily the. The experimental result was obtained using a pipe with the height of 2 m and width of 10 mm. The power loss was decreased with the ratio of 30 dB/m. This low-cost configuration easily collects the reflected light from the liquid surface without complicated aligning.
© (2011) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Cherl-Hee Lee, Jonghun Lee, Jeon-Il Moon, and Kwang Taek Kim "Optical liquid-level sensor using a collimator in a pipe with small holes", Proc. SPIE 8185, Electro-Optical and Infrared Systems: Technology and Applications VIII, 81850T (28 September 2011);

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