Senzorji upogiba in torzije
EnglishSlovensko
UMUM
In-line, fiber-optic polarimetric twist/torsion sensor

This letter presents an optical fiber twist/torsion sensor that utilizes dissimilar polarization-preserving characteristics of standard single-mode and high-birefringence fibers. When only one polarization mode of the highbirefringence fiber is excited, spatial orientation of the E-field vector follows the fibers principal axis orientation, even when the fiber is twisted around its longitudinal axis. This is contrary to a standard single-mode fiber (SMF), where the E-field vector maintains its spatial orientation regardless of the fiber torsional twist. The proposed sensor consists of a short section of standard SMF inserted in between two lead-in polarization-mainlining fibers. Only one mode of the lead-in fiber is excited at the input, while the ratio of both polarization modes is measured at the output side of the fiber assembly in order to determine the torsional twist of a standard SMF. This sensor can be used for measuring unambiguously twist/torsion angles of between 95. The sensor demonstrated very low temperature dependence.

Miniature, all-fiber rotation sensor based on temperature compensated wave plate

This paper presents a miniature, all-fiber fiber optic twist/rotation sensor. The proposed sensor consists of polarization maintaining lead-in fiber (PMF), a short section of standard (fully circularly symmetric) single-mode fiber, which is exposed to twist/axial rotation, an all-fiber quarter-wave wave plate, and a reflective layer. This sensor exploits the inability of a short-section circular symmetric single-mode fiber to change the polarization state or spatial E-field vector orientation of an optical wave when exposed to mechanical twist/rotation. Thus, the twisting of a single-mode fiber in the proposed configuration causes displacement of the lead-in PMF and wave-plate axis. This enables encoding of the twist angle into a power ratio of the leadin PMF LP modes that is propagated in a backward direction by the application of a wave plate, which can be straightforwardly measured by a simple interrogation system. The proposed design allows for compact sensor design with sensors active lengths below 5 mm. The unambiguous angular measurement range of the proposed sensor is 45. An angular resolution better than 0.03 was demonstrated, while the temperature sensitivity proved to be less than 0.011 /C. In order to achieve low temperature sensitivity of the sensing system, a combination of different PMFs was used to eliminate the temperature sensitivity of the PMF based wave plate, which is the main source of temperatureinduced errors in the presented setup.

Quasi-distributed twist/torsion sensor

This paper presents a fiber-optic quasi-distributed in-line twist/rotation sensor. The presented sensor consists of a polarization maintaining lead-in fiber and series of in-line fiber polarizers with integrated semi-reflective mirrors that are interconnected by a standard single mode fiber. Sections of interconnecting single mode define multiple twist/rotation sensitive sensor segments, which can be interrogated individually by a simple optical time domain reflectometer. The presented system exploits the inability of the standard single mode fiber to change the polarization state, i.e. E-field vector orientation of a wave propagating down twisted/rotated fiber. Thus, twisting of the fiber segments between consecutively located polarizers causes modulation of the transmitted optical power along each sensor segment, which is further determined by observation of back-reflected signals from semi-reflective mirrors integrated together with in-line polarizers. A quasi-distributed sensing system with nine sensing segments is demonstrated with twist/rotational resolution better than 0.3 degrees and low cross-talk. The entire system is built out of a small number of simple and efficient optoelectronic components.

Miniature, all-fiber rotation sensor based on temperature compensated wave plate

This letter presents a miniature, all-fiber fiber optic twist/rotation sensor. The proposed sensor consists of polarization maintaining lead-in fiber (PMF), a short section of standard (fully circularly symmetric) single-mode fiber, which is exposed to twist/axial rotation, an all-fiber quarter-wave wave plate, and a reflective layer. This sensor exploits the inability of a short-section circular symmetric single-mode fiber to change the polarization state or spatial E-field vector orientation of an optical wave when exposed to mechanical twist/rotation. Thus, the twisting of a single-mode fiber in the proposed configuration causes displacement of the lead-in PMF and wave-plate axis. This enables encoding of the twist angle into a power ratio of the lead-in PMF linearly polarized modes that is propagated in a backward direction by the application of a wave plate, which can be straightforwardly measured by a simple interrogation system. The proposed design allows for compact sensor design with sensors' active lengths below 5 mm. The unambiguous angular measurement range of the proposed sensor is 45. An angular resolution better than 0.03 was demonstrated, while the temperature sensitivity proved to be <;0.011 /C. To achieve low-temperature sensitivity of the sensing system, a combination of different PMFs was used to eliminate the temperature sensitivity of the PMF-based wave plate, which is the main source of temperature-induced errors in the presented setup.