Abstract

We have developed a simple, noncontact, fiber-optic proximity sensor, using a laser micromachined tap on a single multimode optical fiber. The fiber end is placed near a target surface, and a beam of light is incident from the fiber onto the target. Some fraction of this light is reflected or scattered by the target and coupled back into the fiber. The amount recoupled into the fiber is dependent on the distance between the fiber end and the target surface as well as on other parameters such as the target’s surface roughness. The fiber-optic tap allows us to monitor both the initial amount of light launched down the fiber toward the target and the amount of backreflected light from the target. For a known environment and target surface, variations in source intensity can be compensated for by monitoring the ratio of the two counterpropagating beams.

© 1997 Optical Society of America

Vibration monitoring by using a dynamic proximity sensor with interferometric encoding

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