Open AccessAccurate non-linear calculation model for decoupling thermal and mechanical loading effects in the OBR measurements
Author(s) -
Shaoquan Wang,
Kaspar Lasn
Publication year - 2021
Publication title -
optics express
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.394
H-Index - 271
ISSN - 1094-4087
DOI - 10.1364/oe.410686
Subject(s) - decoupling (probability) , thermal , optics , rayleigh scattering , optical fiber , temperature measurement , materials science , sensitivity (control systems) , physics , electronic engineering , thermodynamics , control engineering , engineering
Fiber optic sensors are increasingly used in several fast-growing industries. Aerospace, energy storage, and the medical sector consider new implementations of optical fibers mainly for condition monitoring purposes. Applications using optical fibers entail measurements of distributed strains and temperatures. However, the spectral shifts of transmitted and reflected light are simultaneously sensitive to both of these influences. This coupled sensitivity can introduce large errors for signal interpretation. An accurate calculation model for signal decoupling is necessary to distinguish pure mechanical strains from pure thermal loading. Approaches where the spectral shift is assumed to vary linearly with temperature give large errors when the temperature variation is high. This investigation derives and validates a new temperature formula that is used for high precision strain and temperature discrimination. The non-linear temperature formula is deduced from physics-based models and is validated with Rayleigh backscattering based OBR measurements. Our calculation approach demonstrates improved accuracy over an extended temperature range. The relationship between strain and temperature effects in the coupled mechanical and thermal loading environment is further studied in detail.