Fiber Optic Radial Displacement Sensor-Based a Beam-Through Technique

Abstract

A fiber optics displacement sensor based on a beam-through technique has wide application due its simplicity, high accuracy, and immune to electromagnetic interference. The fingerprint for such a sensor system is established through the longitudinal displacement. However, it is known that the highest intensity modulation is normally fall at zero distance for the beam-through technique. Thus, it is valuable to take advantage at such optimization position. A novel method is introduced by conducting a fiber optic sensor-based radial displacement. Three types of fiber optic, including 1000, 500, and $265~\mu \text{m}$ core diameters, were employed to optimize the probe. A Gaussian profile is identified to be the fingerprint for the radial displacement sensor, which entirely different with a linear one for longitudinal displacement. The radial displacement fiber optic sensor is a core diameter-dependent. The bandwidth at full width half maximum tends to be broader with the core diameter of a fiber optic. Higher response of the sensor is achieved at the negative side of the Gaussian curve comparable with positive part. It is realized that the sensitivity of the radial sensor is 7 times higher correspond to core diameter and 3 times better performance than the conventional displacement sensor.