Multiple off-axis fiber Bragg gratings for 3D shape sensing

Waltermann, Christian; Bethmann, Konrad; Doering, Alexander; Jiang, Yi; Baumann, Anna Lena; Angelmahr, Martin; Schade, Wolfgang

doi:10.1364/ao.57.008125

Cited by 15 publications

(27 citation statements)

References 15 publications

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“…Each scattering dot used for our experiments was inscribed in the fiber core of standard SMF using a single fs-pulse. The fiber modification was carried out by the Fraunhofer Heinrich Hertz Institute (HHI) Goslar, Germany using the method described in [57,58].…”

Section: Characteristics Of Scattering Dotsmentioning

confidence: 99%

“…Each dot was inscribed using a single fs pulse with a spot size <1 sans-serifμm [58]. The rather large apparent size of the dot as well as its double-peak structure as depicted in Figure 3 stems from the Dirac delta-like increase of backscatter amplitude induced by fs-laser, which could not be properly recovered by the inverse FFT of the OFDR device.…”

Section: Characteristics Of Scattering Dotsmentioning

confidence: 99%

“…Fiber structuring based on scattering dots can be considered as simpler and has fewer demands than an FBG-based approach. FBGs are often written into a fiber using a UV laser and a phase mask, the fiber coating has then to be removed and the fiber recoated after the inscription, resulting in a reduced mechanical stability [48,56,57] whereas the fs-inscribed dots using a point-by-point technique [56,57,58] can be added without the need for uncoating, as the ultrashort pulses are launched to the fiber core and do not damage the coating. In order to manufacture large FBG arrays suitable for long range distributed sensing, online inscription techniques during the fiber drawing process like UV-laser based draw tower gratings [47,48] can be employed.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Enhanced Distributed Fiber Optic Vibration Sensing and Simultaneous Temperature Gradient Sensing Using Traditional C-OTDR and Structured Fiber with Scattering Dots

Hicke

Eisermann

Chruscicki

2019

Sensors

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We present results demonstrating several beneficial effects on distributed fiber optic vibration sensing (DVS) functionality and performance resulting from utilizing standard single mode optical fiber (SMF) with femtosecond laser-inscribed equally-spaced simple scattering dots. This modification is particularly useful when using traditional single-wavelength amplitude-based coherent optical time domain reflectometry (C-OTDR) as sensing method. Local sensitivity is increased in quasi-distributed interferometric sensing zones which are formed by the fiber segments between subsequent pairs of the scattering dots. The otherwise nonlinear transfer function is overwritten with that of an ordinary two-beam interferometer. This linearizes the phase response to monotonous temperature variations. Furthermore, sensitivity fading is mitigated and the demodulation of low-frequency signals is enabled. The modification also allows for the quantitative determination of local temperature gradients directly from the C-OTDR intensity traces. The dots’ reflectivities and thus the induced attenuation can be tuned via the inscription process parameters. Our approach is a simple, robust and cost-effective way to gain these sensing improvements without the need for more sophisticated interrogator technology or more complex fiber structuring, e.g., based on ultra-weak FBG arrays. Our claims are substantiated by experimental evidence.

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Section: Characteristics Of Scattering Dotsmentioning

confidence: 99%

Section: Characteristics Of Scattering Dotsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Enhanced Distributed Fiber Optic Vibration Sensing and Simultaneous Temperature Gradient Sensing Using Traditional C-OTDR and Structured Fiber with Scattering Dots

Hicke

Eisermann

Chruscicki

2019

Sensors

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“…If an external force or change in temperature is induced to the FBG, the periodicity of the inscribed structure will change slightly leading to a specific wavelength shift. So far this sensing principle has been successfully demonstrated for measuring pres sure [3], acceleration, vibration, humidity, magnetic field, the refractive index of fluids, as well as for the reconstruction of its own three-dimensional shape [4] in space, apart from many other.…”

Section: Fiber Optic Sensingmentioning

confidence: 99%

Shaping Spectra within Optical Fibers

Waltermann¹,

Guehlke²,

Koch³

et al. 2019

PhotonicsViews

Self Cite

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A unique fiber‐integrated diffraction grating enables a new kind of ultra miniature high‐resolution spectrometer. Within, all components for optical imaging are encoded directly leading to an outstanding ratio of optical resolution to build size. The entire design comprises only two aligned parts and allows a cost‐effective, customizable production, and robust spectrometers. As an exemplary application we present a compact interrogation system for fiber Bragg grating sensors.

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“…A suitable yet cheaper alternative to multicore sensors are the quasidistributed eccentric FBG sensors (also known as edge-FBGs), which are highly localized FBGs, written off-axis in a single-mode fiber's core (shown in Figure 1). In edge-FBG shape sensors, the directional bending is realized by placing three co-located edge-FBGs with 90 • angular distance from each other [20]. When a single-mode fiber is bent, the field distribution of the fundamental mode moves away from the core's center [20][21][22] (see Figure 1 (b)).…”

mentioning

confidence: 99%

The secret role of undesired physical effects in accurate shape sensing with eccentric FBGs

Roodsari¹,

Freund²,

Angelmahr³

et al. 2022

Preprint

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Fiber optic shape sensors have enabled unique advances in various navigation tasks, from medical tool tracking to industrial applications. Eccentric fiber Bragg gratings (FBG) are cheap and easy-to-fabricate shape sensors that are often interrogated with simple setups. However, using low-cost interrogation systems for such intensity-based quasidistributed sensors introduces further complications to the sensor's signal. Therefore, eccentric FBGs have not been able to accurately estimate complex multi-bend shapes. Here, we present a novel technique to overcome these limitations and provide accurate and precise shape estimation in eccentric FBG sensors. We investigate the most important bending-induced effects in curved optical fibers that are usually eliminated in intensity-based fiber sensors. These effects contain shape deformation information with a higher spatial resolution that we are now able to extract using deep learning techniques. We design a deep learning model based on convolutional neural network that is trained to predict shapes given the sensor's spectra. We also provide a visual explanation, highlighting wavelength elements whose intensities are more relevant in making shape predictions. These findings imply that deep learning techniques benefit from the bending-induced effects that impact the desired signal in a complex manner. This is the first step toward cheap yet accurate fiber shape sensing solutions.

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Multiple off-axis fiber Bragg gratings for 3D shape sensing

Cited by 15 publications

References 15 publications

Enhanced Distributed Fiber Optic Vibration Sensing and Simultaneous Temperature Gradient Sensing Using Traditional C-OTDR and Structured Fiber with Scattering Dots

Enhanced Distributed Fiber Optic Vibration Sensing and Simultaneous Temperature Gradient Sensing Using Traditional C-OTDR and Structured Fiber with Scattering Dots

Shaping Spectra within Optical Fibers

The secret role of undesired physical effects in accurate shape sensing with eccentric FBGs

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