Quasi-distributed Displacement Monitoring Method Based on Double Intensity Modulation

To address the specific requirements of high spatial resolution and high-accuracy detection in slope crack monitoring, this paper proposes a quasi-distributed displacement monitoring method based on dual intensity modulation. The proposed approach reduces additional phase shift noise introduced by conventional phase detection circuits, while offering the advantages of long-range and high-precision measurement. Experimental results demonstrate that the proposed method achieves a displacement sensitivity of 84.81  kHz/mm and a measurement stability of 0.03   mm/h over a sensing fiber length of approximately 1 km.