An optical fiber based technique for continuous level sensing

An optical fiber-based technique for liquid level measurement is proposed. It is based on the power attenuation occurring in an optical fiber, immersed in a liquid, when the liquid level varies. This phenomenon is theoretically approached by using the perturbation theory, which allows information useful for the sensor design to be obtained. The experimental results confirm the theoretical forecasts and allow a low-cost sensor prototype, mainly composed by the optical fiber, immersed in the liquid, and excitation and detection devices, to be set up. This prototype proves to be capable of measuring the liquid level with acceptable sensitivity and repeatability