A Composite Fabry-Perot Interferometric Sensor with the Dual-Cavity Structure for Simultaneous Measurement of High Temperature and Strain.

Ping Xia,Zude Zhou,Caixia Yang,Yuegang Tan,Kang Yun

doi:10.3390/s21154989

Abstract

In this paper, an optical fiber composite Fabry-Perot interferometric (CFPI) sensor capable of simultaneous measurement of high temperature and strain is presented. The CFPI sensor consists of a silica-cavity intrinsic Fabry-Perot interferometer (IFPI) cascading an air-cavity extrinsic Fabry-Perot interferometer (EFPI). The IFPI is constructed at the end of the transmission single-mode fiber (SMF) by splicing a short piece of photonic crystal fiber (PCF) to SMF and then the IFPI is inserted into a quartz capillary with a reflective surface to form a single-ended sliding EFPI. In such a configuration, the IFPI is only sensitive to temperature and the EFPI is sensitive to strain, which allows the achieving of temperature-compensated strain measurement. The experimental results show that the proposed sensor has good high-temperature resistance up to 1000 °C. Strain measurement under high temperatures is demonstrated for high-temperature suitability and stable strain response. Featuring intrinsic safety, compact structure and small size, the proposed CFPI sensor may find important applications in the high-temperature harsh environment.

Highlights

Strain is a vital parameter to characterize the mechanical and thermo-physical properties of the materials, accurate strain measurement has great importance within science and industry [1,2]
It can be seen that total strain including thermal strain and mechanical strain induced by the applied variable load according to steps 1–6 described in Section 3.3, was measured by the extrinsic FabryPerot interferometer (EFPI)
Results of Strain Measurement with Temperature Compensation The temperature-compensated scheme employed in this paper was realized by subtracting the thermal strain from the total strain measured by EFPI, which enabled the discrimination of thermal strain and mechanical strain

Summary

Introduction

Strain is a vital parameter to characterize the mechanical and thermo-physical properties of the materials, accurate strain measurement has great importance within science and industry [1,2] In many applications such as jet engines or power turbines, high-temperature manufacturing and nuclear power operation, extremely high temperatures and severe environments are encountered, which poses significant challenges to current high-temperature strain sensing technology [3,4]. The most widely used high-temperature strain sensors are high-temperature strain gauges, which operates based on gauge resistance as a function of strain They suffer from the inherent disadvantages of vulnerability to electromagnetic interference (EMI), mechanical hysteresis and creep [5] and drift in response due to oxidation [3], which diminish their reliability and accuracy in the above-mentioned environments. FBGs gets brittle and fragile [19] when exposed to high temperatures and would be damaged when improperly handled or subjected to harsh working conditions, leading to packaging difficulties for high-temperature strain measurement

Methods

Results

Conclusion