Nanojet Visualization and Dark-field Imaging of Optically Trapped Vaterite Capsules with Endoscopic Illumination

Fuente: arXiv
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Main Authors: Ushkov, Andrei, Machnev, Andrey, Kolchanov, Denis, Salgals, Toms, Alnis, Janis, Bobrovs, Vjaceslavs, Ginzburg, Pavel
Format: Preprint
Published: 2024
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author Ushkov, Andrei
Machnev, Andrey
Kolchanov, Denis
Salgals, Toms
Alnis, Janis
Bobrovs, Vjaceslavs
Ginzburg, Pavel
author_facet Ushkov, Andrei
Machnev, Andrey
Kolchanov, Denis
Salgals, Toms
Alnis, Janis
Bobrovs, Vjaceslavs
Ginzburg, Pavel
contents Optical responsivity grants biomedical capsules additional capabilities, promoting them towards multifunctional theragnostic nanodevices. In this endeavor, screening candidates under conditions that closely resemble in situ environments is crucial for both the initial optimization and the subsequent inspection stages of development and operation. Optical tweezers equipped with dark-field spectroscopy are among the preferable tools for nanoparticle imaging and refractometry. However, the effectiveness of conventional illumination and light collection arrangements for inspecting anisotropic complex inner composition particles is quite limited due to reduced collection angles, which can result in the omission of features in scattering diagrams. Here we introduce an endoscopic dark-field illumination scheme, where light is launched on an optically trapped particle from a single-mode fiber, immersed into a fluid cell. This arrangement disentangles illumination and collection paths, thus allowing the collection of scattered light with a very high numerical aperture. This methodology is applied to vaterite nanocapsules, which are known to possess strong anisotropic responses. Tweezer configuration allows revealing optical properties for different crystallographic orientations of vaterite, which is complex to do otherwise. Furthermore, endoscopic dark-field images reveal the emergence of polarization-dependent long-range photonic nanojets, which are capable of interacting with nearby particles, demonstrating a new pathway for nanojet image formation.
format Preprint
id arxiv_https___arxiv_org_abs_2404_11303
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Nanojet Visualization and Dark-field Imaging of Optically Trapped Vaterite Capsules with Endoscopic Illumination
Ushkov, Andrei
Machnev, Andrey
Kolchanov, Denis
Salgals, Toms
Alnis, Janis
Bobrovs, Vjaceslavs
Ginzburg, Pavel
Optics
Materials Science
Optical responsivity grants biomedical capsules additional capabilities, promoting them towards multifunctional theragnostic nanodevices. In this endeavor, screening candidates under conditions that closely resemble in situ environments is crucial for both the initial optimization and the subsequent inspection stages of development and operation. Optical tweezers equipped with dark-field spectroscopy are among the preferable tools for nanoparticle imaging and refractometry. However, the effectiveness of conventional illumination and light collection arrangements for inspecting anisotropic complex inner composition particles is quite limited due to reduced collection angles, which can result in the omission of features in scattering diagrams. Here we introduce an endoscopic dark-field illumination scheme, where light is launched on an optically trapped particle from a single-mode fiber, immersed into a fluid cell. This arrangement disentangles illumination and collection paths, thus allowing the collection of scattered light with a very high numerical aperture. This methodology is applied to vaterite nanocapsules, which are known to possess strong anisotropic responses. Tweezer configuration allows revealing optical properties for different crystallographic orientations of vaterite, which is complex to do otherwise. Furthermore, endoscopic dark-field images reveal the emergence of polarization-dependent long-range photonic nanojets, which are capable of interacting with nearby particles, demonstrating a new pathway for nanojet image formation.
title Nanojet Visualization and Dark-field Imaging of Optically Trapped Vaterite Capsules with Endoscopic Illumination
topic Optics
Materials Science
url https://arxiv.org/abs/2404.11303