Fiber optic fused 1×2 coupler as a vibration sensor

Abstract

A simple non-contact vibration sensor is designed using a 1×2 plastic optical fiber coupler based on the principle of extrinsic reflection intensity modulation. A single fiber is used as a sensing head for both transmitting and receiving of light from the reflecting surface of the vibrating object and it exhibits a linear region of about 1 mm with the sensitivity of 2.45 mV/μm. The results show that the sensor can measure the frequency of vibrations up to 1300 Hz with an amplitude resolution of 1 μm. In comparison with a dual-fiber and bifurcated-bundle fiber, it eliminates the dark region and front slope, which facilitates easy alignment.