A method for measuring lateral displacements in structures is proposed based on the motion of a Gaussian optical beam. A sensor is designed and constructed using the free space output of a single mode optical fiber, which well approximates the Gaussian intensity distribution, and is tested in both quasi-static and dynamic displacement modes. Good agreement between the experimental data and the predicted output is obtained for small displacements of the size expected in real buildings. It is envisioned that this sensor could serve as the input to an active control system used to stabilize smart buildings experiencing earthquake and wind loads.

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