A quasi-distributed level sensor based on a bent side-polished plastic optical fibre cable

A flexible quasi-distributed liquid level sensor based on the changes in the light transmittance in a plastic optical fibre (POF) cable is proposed. The measurement points are constituted by small areas created by side-polishing on a curved fibre and the removal of a portion of the core. These points are distributed on each full turn of a coil of fibre built on a cylindrical tube vertically positioned in a tank. The changes between the refractive indices of air and liquid generate a signal power proportional to the position and level of the liquid. The sensor system has been successfully demonstrated in the laboratory, and experimental results of two prototypes with 15 and 18 measurement points in a range of 33 mm and 39 mm respectively and a resolution of 0.08 mm with bend radii of 5 mm and 8 mm are presented.

[1]  Plastic optical fiber builds on MOST success , 2006 .

[2]  S. James,et al.  Fiber-optic liquid-level sensor using a long-period grating. , 2001, Optics letters.

[3]  Cesar Jauregui,et al.  Lateral polishing of bends in plastic optical fibres applied to a multipoint liquid-level measurement sensor , 2007 .

[4]  Joseba Zubia,et al.  Parameters affecting bending losses in graded-index polymer optical fibers , 2001 .

[5]  B. Culshaw,et al.  Propagation of the fundamental mode in curved graded index multimode fiber and its application in sensor systems , 2000, Journal of Lightwave Technology.

[6]  C. Vázquez,et al.  Multi-sensor system using plastic optical fibers for intrinsically safe level measurements , 2004 .

[7]  Kent A. Murphy,et al.  Fiber-optic liquid-level sensor , 1992 .

[8]  Patricia Scully,et al.  Plastic optical fibre sensors and devices , 2000 .

[9]  K Iwamoto,et al.  Liquid-level sensor with optical fibers. , 1992, Applied optics.

[10]  J. A. Martínez,et al.  Fiber-optic liquid-level continuous gauge , 2006 .

[11]  J. Zubía,et al.  Dependence of bending losses on cladding thickness in plastic optical fibers. , 2003, Applied optics.

[12]  B. Wood,et al.  Prediction of light-transmission losses in plastic optical fibers. , 2005, Applied optics.

[13]  Sergei N. Khotiaintsev,et al.  Linear and steplike characteristics in an optical fiber refractometric transducer with hemispherical detection element , 2003 .

[14]  Stefano Selleri,et al.  All‐plastic optical‐fiber level sensor , 2005 .

[15]  D R Hall,et al.  Bend loss in large core multimode optical fiber beam delivery systems. , 1991, Applied optics.

[16]  J. Arrue,et al.  Light power behaviour when bending plastic optical fibres , 1998 .

[17]  J. Zubía,et al.  Analysis of the decrease in attenuation achieved by properly bending plastic optical fibres , 1996 .