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Fiber-Optic Sensors for Measurements of Torsion, Twist and Rotation: A Review †

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ABSTRACT

Optical measurement of mechanical parameters is gaining significant commercial interest in different industry sectors. Torsion, twist and rotation are among the very frequently measured mechanical parameters. Recently, twist/torsion/rotation sensors have become a topic of intense fiber-optic sensor research. Various sensing concepts have been reported. Many of those have different properties and performances, and many of them still need to be proven in out-of-the laboratory use. This paper provides an overview of basic approaches and a review of current state-of-the-art in fiber optic sensors for measurements of torsion, twist and/or rotation.

No MeSH data available.


Finite element method simulation of a total stress distribution in a circularly symmetric fiber and circular non-symmetric fiber (containing two hollow regions): (a,c) show stress distribution when no twist is applied; (b,d) show the case when fibers are exposed to the twist. In case of the twisted fiber with side holes, a non-circularly symmetric stress build-up around the core can be observed, leading to linear birefringence modulation.
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sensors-17-00443-f003: Finite element method simulation of a total stress distribution in a circularly symmetric fiber and circular non-symmetric fiber (containing two hollow regions): (a,c) show stress distribution when no twist is applied; (b,d) show the case when fibers are exposed to the twist. In case of the twisted fiber with side holes, a non-circularly symmetric stress build-up around the core can be observed, leading to linear birefringence modulation.

Mentions: When a linear-birefringent single-mode optical fiber is twisted, its linear birefringence becomes dependent on the fiber’s twist rate (Figure 3). This is due to the circular non-symmetry of the linearly-birefringent fiber, which gives rise to different magnitudes of photo-elastic effects along the fast and the slow axes. The twist induced change in linear birefringence is proportional to the twist magnitude and fiber’s circular non-symmetry (and, consequently, to the fiber’s initial birefringence). Hence, this effect is only present in optical fibers that exhibit initial/intrinsic linear birefringence (Figure 3d). Twisting of a perfectly circuitry symmetric/homogenous optical fiber will not cause the appearance of linear birefringence within the same fiber (Figure 3b). It is, thus, the presence of the fiber’s circular non-symmetry in the fiber that gives rise to a measurement effect that can be observed through observation of changes in the fiber’s linear birefringence caused by torsional twist/rotation.


Fiber-Optic Sensors for Measurements of Torsion, Twist and Rotation: A Review †
Finite element method simulation of a total stress distribution in a circularly symmetric fiber and circular non-symmetric fiber (containing two hollow regions): (a,c) show stress distribution when no twist is applied; (b,d) show the case when fibers are exposed to the twist. In case of the twisted fiber with side holes, a non-circularly symmetric stress build-up around the core can be observed, leading to linear birefringence modulation.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC5375729&req=5

sensors-17-00443-f003: Finite element method simulation of a total stress distribution in a circularly symmetric fiber and circular non-symmetric fiber (containing two hollow regions): (a,c) show stress distribution when no twist is applied; (b,d) show the case when fibers are exposed to the twist. In case of the twisted fiber with side holes, a non-circularly symmetric stress build-up around the core can be observed, leading to linear birefringence modulation.
Mentions: When a linear-birefringent single-mode optical fiber is twisted, its linear birefringence becomes dependent on the fiber’s twist rate (Figure 3). This is due to the circular non-symmetry of the linearly-birefringent fiber, which gives rise to different magnitudes of photo-elastic effects along the fast and the slow axes. The twist induced change in linear birefringence is proportional to the twist magnitude and fiber’s circular non-symmetry (and, consequently, to the fiber’s initial birefringence). Hence, this effect is only present in optical fibers that exhibit initial/intrinsic linear birefringence (Figure 3d). Twisting of a perfectly circuitry symmetric/homogenous optical fiber will not cause the appearance of linear birefringence within the same fiber (Figure 3b). It is, thus, the presence of the fiber’s circular non-symmetry in the fiber that gives rise to a measurement effect that can be observed through observation of changes in the fiber’s linear birefringence caused by torsional twist/rotation.

View Article: PubMed Central - PubMed

ABSTRACT

Optical measurement of mechanical parameters is gaining significant commercial interest in different industry sectors. Torsion, twist and rotation are among the very frequently measured mechanical parameters. Recently, twist/torsion/rotation sensors have become a topic of intense fiber-optic sensor research. Various sensing concepts have been reported. Many of those have different properties and performances, and many of them still need to be proven in out-of-the laboratory use. This paper provides an overview of basic approaches and a review of current state-of-the-art in fiber optic sensors for measurements of torsion, twist and/or rotation.

No MeSH data available.