Use of retroreflector and multi-zeros optical beam for remote monitoring of lateral deformation

In previous paper, we described a principle of free-space optical measurement system for monitoring full-axis (three translational and three rotational) deformation of large and long structures such as bridges, roads, and highways. Accurate full-axis deformation sensing enables progressive displacement measurement for chain of nodes. In this paper, we specialize proposed system in two node lateral displacement detection using retroreflector at remote node. In this system, a remote node consists of only passive element without any power supply or moving parts, so that a remote node can be implemented into a small size and breakdown free stable system. Therefore, it is especially appropriate for severe environment such as nuclear reactor or blast furnace.