Fast low-cost fiber-optic displacement sensor

Abstract

We have developed a fiber-optic sensor for measuring dynamic surface displacements caused by shock waves. Light from a LED emitter is sent through a plastic fiber and reflected from the surface back into the fiber. The intensity of the reflected light gives the distance to the surface. Based on simple principles and utilizing inexpensive components, micrometer and microsecond resolution is achieved at lower cost and easier usage than for interferometric methods and with better reliability than an accelerometer. The sensor is comparatively easy to set up. It is battery operated for reduced sensitivity of electromagnetic interference. The design of the fiber probe facilitates access in narrow and hostile environments.