Demonstration of Large Curvature Radius Shape Sensing Using Optical Frequency Domain Reflectometry in Multi-Core Fibers

Zeen Chen,Tiegen Liu,Junfeng Jiang,Dongfang Zhu,Chenhuan Wang,Zhenyang Ding,Haohan Guo,Yin Yu,Kun Liu,Ming Pan

doi:10.1109/jphot.2021.3098300

Abstract

In distributed shape sensing, the shape reconstruction error is more and more sensitive to the strain measuring error along with curvature radius of reconstructed shape increasing, which causes a notable challenge for large curvature radius shape reconstructing. In this paper, we demonstrate a large curvature radius shape sensing using optical frequency domain reflectometry (OFDR) in multi-core fibers. We construct a theoretical model of strain measuring error and curvature radius reconstructing errors under different curvature radius. In the experiment, by this reconstructing error model, we optimally select the measurable strain resolution and the sensing spatial resolution to realize the shape reconstruction with a large curvature radius and reconstruct two-dimensional (2D) circle shapes of curvature radii from 5 cm to 100 cm. To verify the accuracy of three-dimensional (3D) shape reconstruction, we present a 3D shape sensing validation method based on 3D printing technology. We fabricate a 3D phantom containing a groove with a variable curvature radius of 5 cm to 100 cm. The presented distributed shape sensing system realize to reconstruct this complicated 3D shape. The root-mean-square error of curvature radius between the reconstructed and designed 3D space curves is 7.2 mm and the mean Euclidean distance is 3.4 mm.

Highlights

D ISTRIBUTED shape sensing (DSS) is becoming a hot area of distributed optical fiber sensing [1], which has been applied to fields such as medical robotics [2], industrial robotics [3], aerospace [4], [5], mining industry [6], [7] and so on
The measured curvature radius reconstructing errors are agreed with the numerical stimulation results by the model
By comparing between designed and reconstructed 3D space curves, we can evaluate the results of 3D shape sensing

Summary

Introduction

D ISTRIBUTED shape sensing (DSS) is becoming a hot area of distributed optical fiber sensing [1], which has been applied to fields such as medical robotics [2], industrial robotics [3], aerospace [4], [5], mining industry [6], [7] and so on. Distributed and quasi-distributed optical fiber sensing (DOFS and QDOFS) can achieve directional strain measurements. A DOFS or QDOFS can use a tri-core sensing fiber to measure strain on each core, which is used in a differential geometry model to reconstruct the three-dimensional (3D) shape of the sensing fiber. Fiber Bragg grating (FBG) as a QDOFS technology was firstly used to 3D distributed shape sensing [8]. DOFS use an entire optical fiber as sensing media that is an ideal technology for 3D distributed shape sensing. Szostkiewicz et al used a phase-sensitive optical time-domain reflectometry (phase-OTDR) to achieve DSS. The strain sensing spatial resolution of FBGs and DOFS based on time domain techniques are not very high, which will influence the accuracy of DSS

Methods

Results

Conclusion