Dr. Xiang Wang Profile

Dr. Xiang Wang

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I am a PhD researcher in the Faculty of Aerospace Engineering in TU Delft. My research is distributed fibre optic sensing for structural health monitoring.

Proceedings Article | 9 August 2023 Presentation + Paper

Four-flux model combined with optical coherence tomography technique for non-destructive testing of the colour ground layers of the paintings

Xiang Wang, Andrei Anisimov, Roger Groves

Proceedings Volume 12620, 1262009 (2023) https://doi.org/10.1117/12.2673457

KEYWORDS: Optical coherence tomography, Reflection, Pigments, Nondestructive evaluation, Hyperspectral imaging

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Proceedings Article | 17 May 2022 Presentation + Paper

Plasmon resonance spectral peak shift due to morphing of gold nanoparticles for strain sensing

Xiang Wang, Rinze Benedictus, Roger Groves

Proceedings Volume 12139, 121390S (2022) https://doi.org/10.1117/12.2619170

KEYWORDS: Gold, Neptunium, Nanoparticles, Plasmons, Spherical lenses, Light scattering, Refractive index, Structural health monitoring, Aerospace engineering, Visible radiation

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Proceedings Article | 20 June 2021 Presentation + Paper

Light scattering by gold nanoparticles cured in optical adhesive at optical fibre interfaces

Xiang Wang, Rinze Benedictus, Roger Groves

Proceedings Volume 11782, 1178212 (2021) https://doi.org/10.1117/12.2592308

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This study forms a part of the research in using nanoparticles (NPs) to increase the intensity of light scattering signal in the optical fibres. Increasing the intensity of the backscattered light signal in the optical fibres shows the potential to increase the signal-to-noise ratio in order to improve the sensitivity of the backscatter reflectometry. Doping NPs into the optical fibres can greatly increase the scattered light. However, it is not easy to manufacture NP-doped optical fibres to test different designs. To overcome this problem, in our former work we used the method of dropping refractive index matching liquid containing gold NPs at the optical fibres end tips to investigate the intensity change of the scattered light from the interfaces. In this paper, some new initial experimental results for the scattered light between the optical fibre end tips are shown. Gold NPs have been mixed into the optical adhesive (Norland) and is then dropped and cured at the optical fibre end tips. A backscatter reflectometer (LUNA ODiSI-B) was used in the experiment to measure the intensity of scattered light distribution between the optical fibre end tips. We investigated 4 cases of light scattering between the optical fibre end tips: (i) the backscattered light intensity distribution in the case of the air gap between the optical fibre end tips; (ii) the backscattered light intensity distribution with optical adhesive between the optical fibre end tips; (iii) the backscattered light intensity distribution with optical adhesive containing gold NPs (gold nanopowder (<100 nm), Sigma Aldrich) between the optical fibre end tips before curing process and (iv) the backscattered light intensity distribution with optical adhesive containing gold NPs between the optical fibre end tips after the curing process. Our initial findings are that the scattered light by gold NPs at the optical fibre interfaces can be detected by the backscatter reflectometer. By obtaining the differential signal between the distributed light scattering by cured optical adhesive containing gold NPs and only optical adhesive between the optical fibre end tips, the light scattered by the gold NPs has be determined.

Proceedings Article | 1 April 2020 Presentation + Paper

Light scattering and rheological effects in an optical fibre coupled nanoparticle suspension

Xiang Wang, Rinze Benedictus, Roger Groves

Proceedings Volume 11354, 113540V (2020) https://doi.org/10.1117/12.2556799

KEYWORDS: Optical fibers, Liquids, Nanoparticles, Gold, Light scattering, Refractive index, Photodetectors, Microscopes, Geometrical optics, Collimation

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This study forms the first part of research into enhancing the forward and back scattering of light in an optical fibre using nanoparticles (NPs). This approach has the potential to enhance the sensitivity of optical fibre sensing by increasing the signal-to-noise ratio. The work described in this paper is focused on understanding the scattering of light by a suspension of NPs in refractive index matching liquid. It was noted early in the experimental work that rheological effects related to the viscosity and flow of the liquid affect the scattered light measured and therefore these effects are considered in the analysis. Gold nanoparticles in the tens to hundreds of micrometre size range were selected as the scattering particles based on their optical properties. These are suspended in a refractive index liquid with a similar refractive index to the optical fibre core. Effort was needed to transfer the NPs from their aqueous sodium citrate solution to the paraffin based solution. We investigated two types of interaction with the optical fibre: (i) dropping the NP suspension onto the end of a single-mode optical fibre and (ii) using the NP suspension as an interface between two single-mode optical fibres. It was noted that the surface tension of the liquid, the diameter of the fibre and the spacing between the fibres in case (ii) influence the reflected and transmitted light. In case of excess liquid, droplets flowed down the fibre and interestingly in case (ii) modified the reflected and forward transmitted light as it passed across the fibre interface. Our initial findings are that the influence of the gap between two optical fibres decreased after dropping refractive index liquid into the gap after fibre collimation, which is a beneficial result for understanding the influence of scattered light from a liquid containing NPs. Note, the position between the two fibres can also change due to the weight of the droplet and the fibre ends had to be re-collimated to investigate the influence of the moving droplets. These results will be expanded by additional experiments and modelling of the scattering from the nanoparticales and droplets.

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