Temperature Cross-sensitivity Compensation in Liquid Level Sensor Using Mach-Zehnder Interferometers

摘要

This paper presents a technique for temperature cross-sensitivity compensation in liquid level sensor based on an in-fiberMach-Zehnder interferometer. By using a commercial splicing machine and three different fibers, it is possible to constructa liquid level sensor with range of 120 mm and submillimeter resolution (0.88 mm). The sensor arrange is anchorage intoa glass pipette, where the liquid level can be easily supervised. A broadband source is used to illuminate the sensor andthe transmitted spectrum is monitored with an optical spectrum analyzer with 30 pm resolution. The interference pattern,created by the interferometer, is analyzed with either the traditional method of tracking peaks and dips or the overallspectrum envelope. These interferometers are sensitive to temperature variations, leading measurements errors on theliquid level estimation. Thus, an analysis of the temperature effect in the sensor response is performed. The result showsthat the proposed technique reduces the sensor temperature cross-sensitivity by more than an order of magnitude. Withtraditional method (using peaks and dips), the value achieved was ~9.595 mm/℃, whereas the proposed approach basedon the spectrum envelope leads to a temperature cross-sensitivity of about 0.562 mm/℃. The proposed sensor arrange issuitable for industrial applications such as chemical processing, fuel storage and transportation systems, oiltanks/reservoirs, and treatment plants, where there is simultaneous variations of temperature and level.