Some Advanced Fiber-Optical Amplitude Modulated Reflection Displacement and Refractive Index Sensors

J Verkelis,V Kleiza

doi:10.15388/na.2007.12.2.14712

Abstract

Some advanced fiber-optic amplitude modulated reflection displacement sensors and refractive index sensors have been developed. An improved three-fiber displacement sensor has been investigated as a refractive index sensor by computer simulations in a large interval of displacement. Some new regularities have been revealed. A reflection fiber-optic displacement sensor of novel configuration, consisting of double optical-pair fibers with a definite angle between the measuring tips of fibers in the pairs has been proposed, designed, and experimentally investigated to indicate and measure the displacement and refractive index of gas and liquid water solutions. The proposed displacement sensor and refractive index sensor configuration improves the measuring sensitivity in comparison with the known measuring methods. The refractive index sensor sensitivity Snsub = 4 × 10−7 RIU/mV was achieved. The displacement sensor sensitivity is Ssub = 1702 mV/µm in air (n = 1.00027).

Highlights

Fiber-optic sensors have found many applications in recent years
The light in them was launched onto the mirror through the incoming fiber, and a part of the reflected light was detected by the two outgoing fibers and photodiodes
It is interesting to investigate these sensors as refractive index sensors

Summary

Introduction

Fiber-optic sensors have found many applications in recent years. Physical and chemical effects have been used to develop a variety of interferometric sensors for monitoring displacement [1], pressure [2], and other parameters [3]. One of the limitations of these sensors is that they perform well within laboratories, but in the field of applications their performance declines due to their sensitivity to vibration and temperature [4]. Intensity-modulated fiber-optic sensors have found application [5, 6]. Fiber-optic amplitude-modulated compensated displacement sensors as refractive index sensors in [7, 8] are proposed and investigated. The light in them was launched onto the mirror through the incoming fiber, and a part of the reflected light was detected by the two outgoing fibers and photodiodes.

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Conclusion