Fabrication and characterization of a fiber-optic temperature sensor based on NaCl solution

This chapter discusses a fiber optic temperature sensor was developed using an aqueous solution of sodium chloride and an Optical Time-Domain Reflectometer (OTDR) to measure temperature at a long distance. To measure real-time temperature, many different types of temperature sensors, including thermocouple, resistance temperature detector, thermopile, and thermistor, have been developed and commercialized. To overcome these problems, various fiber-optic temperature sensors have been investigated as a promising candidate. Fiber-optic fiber coupler connectors were installed on the both ends of the optical fiber in order to easily and exactly connect with the sensing probe and the OTDR device. The fiber-optic temperature sensor system consists of a sensing probe, a transmitting optical fiber, an OTDR, and a laptop computer. The chapter describes the optimum concentration of the NaCl solution and the optimum wavelength of the light source and then obtained the relationship between the optical power of the fiber-optic temperature sensor and the temperature of water.