Limits...
Compact Optical Fiber 3D Shape Sensor Based on a Pair of Orthogonal Tilted Fiber Bragg Gratings.

Feng D, Zhou W, Qiao X, Albert J - Sci Rep (2015)

Bottom Line: In this work, a compact fiber-optic 3D shape sensor consisting of two serially connected 2° tilted fiber Bragg gratings (TFBGs) is proposed, where the orientations of the grating planes of the two TFBGs are orthogonal.The measurement of the reflective transmission spectrum from the pair of TFBGs was implemented by Fresnel reflection of the cleaved fiber end.In the third (axial) direction, the strain is obtained directly by the shift of the TFBG Bragg wavelengths with a sensitivity of 1.06 pm/με.

View Article: PubMed Central - PubMed

Affiliation: Department of Physics, Northwest University, Xi'an, 710069, China.

ABSTRACT
In this work, a compact fiber-optic 3D shape sensor consisting of two serially connected 2° tilted fiber Bragg gratings (TFBGs) is proposed, where the orientations of the grating planes of the two TFBGs are orthogonal. The measurement of the reflective transmission spectrum from the pair of TFBGs was implemented by Fresnel reflection of the cleaved fiber end. The two groups of cladding mode resonances in the reflection spectrum respond differentially to bending, which allows for the unique determination of the magnitude and orientation of the bend plane (i.e. with a ± 180 degree uncertainty). Bending responses ranging from -0.33 to + 0.21 dB/m(-1) (depending on orientation) are experimentally demonstrated with bending from 0 to 3.03 m(-1). In the third (axial) direction, the strain is obtained directly by the shift of the TFBG Bragg wavelengths with a sensitivity of 1.06 pm/με.

No MeSH data available.


Related in: MedlinePlus

(a) Spectra responses under different temperatures. Insert indicates the wavelength shifts of TFBG1 and TFBG2 versus temperature, respectively; (b) Overlap of the two spectra for temperatures of 25.2 °C and 64.8 °C, using the Bragg peak to determine the amount of shift needed. The insert shows perfect overlap between the resonances used to measure curvature (3.2 nm from the Bragg peak).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC4663507&req=5

f6: (a) Spectra responses under different temperatures. Insert indicates the wavelength shifts of TFBG1 and TFBG2 versus temperature, respectively; (b) Overlap of the two spectra for temperatures of 25.2 °C and 64.8 °C, using the Bragg peak to determine the amount of shift needed. The insert shows perfect overlap between the resonances used to measure curvature (3.2 nm from the Bragg peak).

Mentions: Lastly, the third direction for full 3D shape sensing is discussed. Similarly with normal FBGs23, the wavelength of the core mode resonance of a TFBG depends on two factors: the effective index of the fiber core and the axial grating period Λ. When the sensor is stretched symmetrically along z-axis, both factors are changed, contributing to a shift of the Bragg wavelength. Figure 5 shows the experimental results for the red-shifts of the TFBG1 spectrum (as shown in insert) and the strain sensitives K1 to TFBG1 (blue line) and K2 to TFBG2 (red line), respectively. These wavelength shifts provide a measure of axial strain as long as the temperature of the system does not change: the axial strain sensitivity of these TFBGs suffers from the same cross-sensitivity to temperature as the widely used FBG strain sensors. In order to be able to determine the 3D shape uniquely with this proposed novel device, a separate temperature measurement is required and its effect removed from the measured spectral shifts. As shown in Fig. 6, the spectra show negligible deformation to temperature perturbations (which can be clearly seen by overlapping spectra under different temperatures from 25.2 to 65 °C, as seen in Fig. 6(b)) with the power change within ± 0.01 dB for the resonance 3.2 nm from the Bragg peak, apart from the overall wavelength shift with a sensitivity ~10.5 pm/°C (as shown in insert in Fig. 6(a)). This shows that temperature-induced shifts have no effect on curvature measurements.


Compact Optical Fiber 3D Shape Sensor Based on a Pair of Orthogonal Tilted Fiber Bragg Gratings.

Feng D, Zhou W, Qiao X, Albert J - Sci Rep (2015)

(a) Spectra responses under different temperatures. Insert indicates the wavelength shifts of TFBG1 and TFBG2 versus temperature, respectively; (b) Overlap of the two spectra for temperatures of 25.2 °C and 64.8 °C, using the Bragg peak to determine the amount of shift needed. The insert shows perfect overlap between the resonances used to measure curvature (3.2 nm from the Bragg peak).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4663507&req=5

f6: (a) Spectra responses under different temperatures. Insert indicates the wavelength shifts of TFBG1 and TFBG2 versus temperature, respectively; (b) Overlap of the two spectra for temperatures of 25.2 °C and 64.8 °C, using the Bragg peak to determine the amount of shift needed. The insert shows perfect overlap between the resonances used to measure curvature (3.2 nm from the Bragg peak).
Mentions: Lastly, the third direction for full 3D shape sensing is discussed. Similarly with normal FBGs23, the wavelength of the core mode resonance of a TFBG depends on two factors: the effective index of the fiber core and the axial grating period Λ. When the sensor is stretched symmetrically along z-axis, both factors are changed, contributing to a shift of the Bragg wavelength. Figure 5 shows the experimental results for the red-shifts of the TFBG1 spectrum (as shown in insert) and the strain sensitives K1 to TFBG1 (blue line) and K2 to TFBG2 (red line), respectively. These wavelength shifts provide a measure of axial strain as long as the temperature of the system does not change: the axial strain sensitivity of these TFBGs suffers from the same cross-sensitivity to temperature as the widely used FBG strain sensors. In order to be able to determine the 3D shape uniquely with this proposed novel device, a separate temperature measurement is required and its effect removed from the measured spectral shifts. As shown in Fig. 6, the spectra show negligible deformation to temperature perturbations (which can be clearly seen by overlapping spectra under different temperatures from 25.2 to 65 °C, as seen in Fig. 6(b)) with the power change within ± 0.01 dB for the resonance 3.2 nm from the Bragg peak, apart from the overall wavelength shift with a sensitivity ~10.5 pm/°C (as shown in insert in Fig. 6(a)). This shows that temperature-induced shifts have no effect on curvature measurements.

Bottom Line: In this work, a compact fiber-optic 3D shape sensor consisting of two serially connected 2° tilted fiber Bragg gratings (TFBGs) is proposed, where the orientations of the grating planes of the two TFBGs are orthogonal.The measurement of the reflective transmission spectrum from the pair of TFBGs was implemented by Fresnel reflection of the cleaved fiber end.In the third (axial) direction, the strain is obtained directly by the shift of the TFBG Bragg wavelengths with a sensitivity of 1.06 pm/με.

View Article: PubMed Central - PubMed

Affiliation: Department of Physics, Northwest University, Xi'an, 710069, China.

ABSTRACT
In this work, a compact fiber-optic 3D shape sensor consisting of two serially connected 2° tilted fiber Bragg gratings (TFBGs) is proposed, where the orientations of the grating planes of the two TFBGs are orthogonal. The measurement of the reflective transmission spectrum from the pair of TFBGs was implemented by Fresnel reflection of the cleaved fiber end. The two groups of cladding mode resonances in the reflection spectrum respond differentially to bending, which allows for the unique determination of the magnitude and orientation of the bend plane (i.e. with a ± 180 degree uncertainty). Bending responses ranging from -0.33 to + 0.21 dB/m(-1) (depending on orientation) are experimentally demonstrated with bending from 0 to 3.03 m(-1). In the third (axial) direction, the strain is obtained directly by the shift of the TFBG Bragg wavelengths with a sensitivity of 1.06 pm/με.

No MeSH data available.


Related in: MedlinePlus