Large-range fiber microsphere micro-displacement sensor

Abstract A new method for detecting micro-displacement by using fiber end-face microsphere coupling is proposed to realize an accurate detection of large-scale micro-displacement. This fiber end-face microsphere is equivalent to a lens, which has a certain convergence effect on light, thereby improving the coupling efficiency of the fiber. In the experiment, a single-mode fiber with a core diameter of 9 μm and a cladding diameter of 125 μm was used, and the fiber end face was cut by using a fusion splicer for manual discharge. The fiber end-face microspheres were obtained given the surface tension of the fiber. At an emission aligned with the center of the receiving fiber end-face microspheres, the distance between the two fiber microspheres changed, and the light intensity received by the receiving end-fiber microspheres also changed, thereby causing intensity modulation. Experiment results showed that the sensitivity of the sensor is 0.00401 dBm/μm in the range of 0–3725 μm displacement at room temperature with a linear fit of 94.79%.Thereinto, the sensitivity is 0.0064 dBm/μm in the range of 800–1775 μm with a linear fit of 99.88%. The sensor has a wide detection range, favorable linearity, rapid response, simple manufacturing process, and low cost. Furthermore, this sensor is suitable for working in a severe environment with strong electromagnetic interference and is popular and applicable to the field of micro-displacement detection.