Fiber Optic Displacement Sensor for Medal Detection using Fiber Bundled Probe

A simple fiber optic displacement sensor (FODS) based on intensity modulation technique is investigated using a bundle multimode plastic fiber as a probe for various medals detection. The sensor consists of a light source, a probe, and photodiode detector. The sensor is capable of measuring displacements of flat medals ranging from 0.05 to 4.2 mm using a red light source of wavelength 630 mn. The highest sensitivity of the sensor is found to be 0.0048 mV/mu m over 50-650 mu m for the gold medal. The sensor is highly sensitive at the front slope and very useful for close distance target. The simplicity of the design, high sensitivity, long dynamic range and the low cost of the fabrication make it suitable for wider applications in industries as position control and micro displacement measurement in the hazardous region.