Study On FBG-Based Sensor For Simultaneous Dual-Measurement Of Pressure And Temperature

Optical Fiber grating (FBG) is a kind of optical fiber passive device; it has been developed quickly and used widely in recent years. Compare with the tradition sensors, FBG sensors have many unique advantages, such as simple structure, good reliability, strong corrosion resistance, strong anti-interference of electromagnetism and easy to constitute to spread the feeling network etc, so more and more researchers and engineers show great interests in the applications of the fiber Bragg grating (FBG) sensing and measuring technologies. The main work and results in this paper are following:Firstly, base on the principle of light travel in FBG, the strain and temperature sensing properties have been analyzed and the coupling effect between strain and temperature has also been considered. Then, the principle and technique for temperature compensation are given when we use FBG as strain sensor.Secondly, according to the pressure sensing principle, a novel pressure sensor based on circular plate diaphragm- equal strength cantilever is presented. Due to the dual-FBGs differential measurement structure, the problem of temperature-strain cross-sensitivity on the pressure sensor is improved; and furthermore, the sensitivity of the sensor is increased theoretically.Thirdly, in consideration of the monitoring of pore-water pressure of dam and roadbed, a novel pore-water pressure sensor structure for simultaneous measuring pressure and temperature has been designed. Then groups of experiments have been carried out to show the properties of pressure measuring, temperate measuring and temperature self-compensation. The results indicate that the pore-water pressure sensor based on FBG has good linearity, repetition; immunity of temperature changes. Such kind of FBG-based pore-water pressure sensor can be used in practical monitoring.