Micro-displacement Sensor with Temperature Compensation based on Double-ball Cascade and Fiber Bragg Grating

According to the double-ball structure and the sensing characteristics of the fiber Bragg grating (FBG), a micro-displacement sensor with temperature compensation is proposed and verified experimentally. The sensing structure is made of a FBG and a double-ball cascade. The first ball is used to excite the cladding mode, and the second can get the coupling interference between the cladding mode and the core mode. In the light of Bragg grating's inherent temperature characteristic, it can only be used to estimate temperature. The drift of single mode fiber interference dip and Bragg grating transmission spectrum are independent of each other. It reduces the influence of cross sensitivity between temperature and displacement. The experimental results show that the micro-displacement and temperature detection ranges are 0~0.16mm and 20~160°C; the micro-displacement and temperature sensitivities of the sensor are -89.892 nm/mm and -0.088 nm/°C, respectively. And the temperature sensitivity of FBG dip is 0.012 nm/°C. The micro-displacement measurement with temperature-compensated can be obtained by calculating the sensing matrix.