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.
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机译：在这项工作中，提出了一种紧凑的光纤3D形状传感器，该传感器由两个串联的2°倾斜光纤布拉格光栅（TFBG）组成，其中两个TFBG的光栅平面的方向是正交的。来自一对TFBG的反射透射光谱的测量是通过劈开光纤末端的菲涅耳反射来实现的。反射光谱中的两组包层模式共振对弯曲的响应不同，这可以唯一确定弯曲平面的大小和方向（即具有±180度的不确定性）。弯曲响应范围从-0.33到+ 0.21 dB / m -1 （取决于方向）在0到3.03 m -1 的弯曲范围内得到了实验证明。在第三（轴向）方向上，应变是通过TFBG布拉格波长的移动直接获得的，灵敏度为1.06 pm /με。
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