<title>Gaussian beam displacement sensor for monitoring interstory drift in smart buildings</title>

Abstract

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.

<title>Laser technique for measuring three-dimensional interstory drift</title>

“…Ref. [3] uses four PSDs arranged in a rectangle as shown in Fig.3 to detect the displacement of projection. Comparing Fig.2 (a) and Fig.2 (b), one can conclude that, both lateral translation and chord drift result in the same displacement of projection at the plane of PSDs.…”

<title>Laser crosshair projection technique for interstory drift measurement</title>

“…An alternative method known as the Gaussian Beam Displacement Sensor (GBDS) has been investigated by Bennett, et al [3]. This sensor is designed to detect the motion of the free space beam emerging from a single mode optical fiber; this output has a radially symmetric intensity distribution which can be closely approximated by a classical Gaussian beam.…”

“…The rotation stage was used to create angular input displacements which were measured using the detector outputs with equations (1), (2) and (3). As depicted in Figure 7, the measured angles were plotted against the input angles, resulting in a slope of 0.970, and an r value of 0.996.…”