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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.


Twist/rotation sensor employing a Sagnac interferometer.
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sensors-17-00443-f004: Twist/rotation sensor employing a Sagnac interferometer.

Mentions: Known approaches for the measurements of linear birefringence variations in optical fibers usually involve interferometric methods. Among these methods, Sagnac interferometers/loop mirrors seems to dominate. The Sagnac interferometer/loop mirror provides a straightforward way for measurement of a fiber’s birefringence. When a section of single-mode fiber in the loop is replaced by linearly birefringent fiber, the birefringent fiber induces a wavelength dependent nonreciprocal phase shift among waves propagating in opposite directions within the fiber loop [12,13] as illustrated in Figure 4. This results in the loop’s distinctive spectral fringe pattern, with period and phase dependent on the inserted fiber’s birefringence and length, which makes spectral interrogation a preferred choice for extraction of a sensor signal. The spectral fringe contrast is maximum when both birefringent modes are excited equally, thus, some sort of polarization control is usually needed within the loop.


Fiber-Optic Sensors for Measurements of Torsion, Twist and Rotation: A Review †
Twist/rotation sensor employing a Sagnac interferometer.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

sensors-17-00443-f004: Twist/rotation sensor employing a Sagnac interferometer.
Mentions: Known approaches for the measurements of linear birefringence variations in optical fibers usually involve interferometric methods. Among these methods, Sagnac interferometers/loop mirrors seems to dominate. The Sagnac interferometer/loop mirror provides a straightforward way for measurement of a fiber’s birefringence. When a section of single-mode fiber in the loop is replaced by linearly birefringent fiber, the birefringent fiber induces a wavelength dependent nonreciprocal phase shift among waves propagating in opposite directions within the fiber loop [12,13] as illustrated in Figure 4. This results in the loop’s distinctive spectral fringe pattern, with period and phase dependent on the inserted fiber’s birefringence and length, which makes spectral interrogation a preferred choice for extraction of a sensor signal. The spectral fringe contrast is maximum when both birefringent modes are excited equally, thus, some sort of polarization control is usually needed within the loop.

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.