Development and comparison of fiber-optic water temperature sensors with different sized metal caps

Abstract

Keywords: fiber-optic temperature sensor, sensing probe, metal cap, infrared optical fiberIn this study, we developed a contact-type fiber-optic temperature sensor (CFOTS) for remote and real-time measurements of water temperature. The CFOTS consisted of a sensing probe, a transmitting infrared (IR) optical fiber, a light measuring device, and a laptop. The transmitting IR optical fiber was a polycrystalline infrared (PIR) fiber based on silver halides (AgCl:AgBr). The light-measuring device was a thermopile-type photodiode detector module. The sensing probes were metal caps fabricated from metals of high thermal conductivity: copper and aluminum. Several metal caps of different materials and different inner diameters (1.5, 2.5, and 3.5 mm) were prepared and characterized to identify the optimal material and size of the sensing probe in terms of its detection performance. The CFOTS measured the water temperature of a sample in an oil bath over a range of 30-70 °C. The experimental results showed that the copper metal cap with an inner diameter of 3.5 mm was the best water temperature sensor.