An Extrinsic Fiber Fabry-Perot Interferometer for Dynamic Displacement Measurement

Abstract

This paper presents a fiber-based Fabry-Perot interferometer to determine dynamic displacement such as in vibration tracking of an oscillating target. This sensor exploits the dual-cavity principle in the sensing arm to achieve nonambiguous directional displacement measurements and has a measurement range of ~120 μm for a sinusoidal excitation signal up to 125 Hz. By adopting a modified fringe counting technique to take into account all the appropriate points over the two sets of interference signals thereby generated due to target movement, a resolution of ~40 nm can be achieved. The results obtained from the fiber interferometric sensor employed to measure various displacement signals show good agreement with prediction.Index Terms -displacement, Fabry-Perot interferometer, nonambiguous measurement, double cavity, fiber sensor.

An extrinsic fiber Fabry-Perot interferometer for dynamic displacement measurement

“…Hence, no additional reference arm is required, leading to a reduction in optical components and hence cost savings when compared to either the Michelson or Mach-Zehnder interferometer. Moreover, the FFPI also exhibits superior performance in terms of the frequency bandwidth, sensitivity as well as precision [5][6][7], and has been frequently employed in velocity, strain, acoustics, temperature, micro-assembly process and vibration measurement [8][9][10].…”

“…In recent work, an extrinsic fiber-based FabryPerot interferometric sensor has been developed for small displacement measurement without directional ambiguity [5]. In this work, we, however, exploited the fiber interferometer with a quadrature phase condition generated optically subject to three different excitation regimes (sinusoidal, triangular, and square waves) for investigating the dynamic displacement analysis.…”

Resolution Improvement in Fabry-Perot Displacement Sensor Based on Fringe Counting Method

“…In contrast, FCM technique offers an algorithm with less complex data processing in displacement detection. Despite the simplicity of the [13]- [14]. Therefore, in this paper, a new fringe counting mechanism has been developed in order to enhance the FPDS resolution and called as the improved FCM technique.…”