Displacement Sensors

doi:10.1117/3.1002910.ch9

Book: Fiber Optic Sensors: Fundamentals and Applications, Fourth Edition

Author(s): Trevor W. MacDougall, Alexis Mendez, David A. Krohn

Published: 2015

https://doi.org/10.1117/3.1002910.ch9

Author Affiliations +

Abstract

Fiber optic displacement sensors are multipurpose devices that find uses in a broad range of industrial, automotive, aerospace, military, and medical applications. Optical-fiber-based displacement sensors are attractive because of their EM and RF immunity, i.e., their capability to operate in extreme environments-from cryogenic to elevated temperatures-under vacuum or in the presence of strong vibrations. For such reasons, these devices are commonly used in aeronautic and aerospace applications, nuclear power plants, and robotic systems, and for civil engineering and geotechnical measurements, and many other harsh or hazardous location type applications. In general, such sensors are most typically used as devices to measure and/ or monitor relative movement (displacement). However, they can also be utilized as sensors for position, thickness, concentricity, alignment, proximity, rotation, torque, etc. Furthermore, depending on their design and configuration, they can perform their measurement via direct contact or non-contact. Several different techniques are commonly used in the design of fiber optic displacement sensors. Among the most common are the following: Reflective technology Microbending technology Modulating technology Fabry-Pérot technology Fiber Bragg grating technology Next, we shall review each one of the types and provide more details on their design features and characteristics.