A novel liquid level monitoring sensor system using a fiber Bragg grating

A fiber optic liquid level sensor based on the strain sensing by a fiber Bragg grating (FBG) is proposed and demonstrated. The FBG packaged on a thin cantilever beam so that the elongation and contraction of the FBG indicate a liquid level change. The strain response of FBG has been carried out and the shift in the Bragg wavelength shows a very good linearity during rise and fall of liquid level. The sensitivity is approximately 17.8 pm/cm for a liquid level variation of 30 cm. The liquid level monitoring system achieve good reversibility and repeatability. Three kinds of demodulating methods are adopted to detect the wavelength shift.