A temperature self-compensation submicron displacement fbg sensor with tilt parallel-suspended dual-optical fibers

A temperature self-compensating displacement sensor based on fiber Bragg grating (FBG) was developed to measure micro-displacement. This design is composed of a slider, two flexible springs, a probe, and two optical fibers. Both fibers, which are inscribed with FBGs, are tightly suspended in a tilt parallel manner and this structural design allows to tailor the displacement sensing range depending on different sensing requirements or ranges. Furthermore, the difference between the responses of two FBGs is sensitive to the micro axial-movement while insensitive to the temperature. The sensing model with the temperature compensated FBG-based displacement sensor is derived and introduced in detail. Experimental results demonstrate that the sensor's sensitivity achieves 1518.6 pm/mm, and its range is 0–0.5 mm. The dynamic experiment indicates that the measured result of the designed sensor is in line with the values of a commercial laser displacement sensor which effectively validates the feasibility of the proposed sensor to measure a micro-displacement. Besides, the micro-displacement detection capability with the temperature self-compensation, the designed sensor can support temperature measurement within 20 °C− 50 °C.