In this paper, we present a fiber sensor using a fiber Bragg grating encapsulated in a half-polymer-filled metal cylinder for measuring liquid level variation. The operating mechanism of this novel design is based on transferring radial pressure into axial strain to induce Bragg wavelength shift. Referencing to a same liquid level (of a liquid reservoir or reference sensor), a group of such sensor interrogated simultaneously by a FBG interrogator can construct a differential. The design and packaging of simple, small, and low cost sensor heads, used for continuous liquid level measurement using uniformly thinned (etched) optical fiber Bragg grating (FBG) are proposed. The sensor system consists of only an FBG and a simple detection system. Characterization is performed by submerging.
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