Comparative study on resolution enhancements in fluorescence-structured illumination Fresnel incoherent correlation holography

Author(s):

Jeon, Philjun; Kim, Jongwu; Lee, Heejung; Kwon, Hyuk-Sang & young Kim, Dug

Abstract:

“Fresnel incoherent correlation holography (FINCH) is a new approach for incoherent holography, which also has enhancement in the transverse resolution. Structured illumination microscopy (SIM) is another promising super-resolution technique. SI-FINCH, the combination of SIM and FINCH, has been demonstrated lately for scattering objects. In this study, we extended the application of SI-FINCH toward fluorescent microscopy. We have built a versatile multimodal microscopy system that can obtain images of four different imaging schemes: conventional fluorescence microscopy, FINCH, SIM, and SI-FINCH. Resolution enhancements were demonstrated by comparing the point spread functions (PSFs) of the four different imaging systems by using fluorescence beads of 1-μm diameter.”

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Publication: Optics Express
Issue/Year: Optics Express, Volume 29; Number 6; Pages 9231; 2021
DOI: 10.1364/oe.417206

2.5D Microscopy: Fast, High-Throughput Imaging via Volumetric Projection for Quantitative Subcellular Analysis

Author(s):

Ren, Jinhan & Han, Kyu Young

Abstract:

“Imaging-based single-cell analysis is essential to study the expression level and functions of biomolecules at subcellular resolution. However, its low throughput has prevented the measurement of numerous cellular features from multiples cells in a rapid and efficient manner. Here we report 2.5D microscopy that significantly improves the throughput of fluorescence imaging systems while maintaining high-resolution and single-molecule sensitivity. Instead of sequential z-scanning, volumetric information is projected onto a 2D image plane in a single shot by engineering the emitted fluorescence light. Our approach provides an improved imaging speed and uniform focal response within a specific imaging depth, which enabled us to perform quantitative single-molecule RNA measurements over a 2 × 2 mm² region within an imaging depth of ∼5 μm for mammalian cells in <10 min and immunofluorescence imaging at a >30 Hz volumetric frame rate with reduced photobleaching. Our microscope also offers the ability of multicolor imaging, depth control, and super-resolution imaging.”

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Publication: ACS Photonics
Issue/Year: ACS Photonics, Volume 8; Number 3; Pages 933-942; 2021
DOI: 10.1021/acsphotonics.1c00012

3D reconstruction of weakly scattering objects from 2D intensity-only measurements using the Wolf transform

Author(s):

Ayoub, Ahmed B.; Lim, Joowon; Antoine, Elizabeth E. & Psaltis, Demetri

Abstract:

“A new approach to optical diffraction tomography (ODT) based on intensity measurements is presented. By applying the Wolf transform directly to intensity measurements, we observed unexpected behavior in the 3D reconstruction of the sample. Such a reconstruction does not explicitly represent a quantitative measure of the refractive index of the sample; however, it contains interesting qualitative information. This 3D reconstruction exhibits edge enhancement and contrast enhancement for nanostructures compared with the conventional 3D refractive index reconstruction and thus could be used to localize nanoparticles such as lipids inside a biological sample.”

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Publication: Optics Express
Issue/Year: Optics Express, Volume 29; Number 3; Pages 3976; 2021
DOI: 10.1364/oe.414543

Giant Helical Dichroism of Single Chiral Nanostructures with Photonic Orbital Angular Momentum

Author(s):

Ni, Jincheng; Liu, Shunli; Hu, Guangwei; Hu, Yanlei; Lao, Zhaoxin; Li, Jiawen; Zhang, Qing; Wu, Dong; Dong, Shaohua; Chu, Jiaru & Qiu, Cheng-Wei

Abstract:

“Optical activity, demonstrating the chiral light-matter interaction, has attracted tremendous attention in both fundamental theoretical research and advanced applications of high-efficiency enantioselective sensing and next-generation chiroptical spectroscopic techniques. However, conventional chiroptical responses are normally limited in large assemblies of chiral materials by circularly polarized light, exhibiting extremely weak chiroptical signals in a single chiral nanostructure. Here, we demonstrate that an alternative chiral freedom of light—orbital angular momentum—can be utilized for generating strong helical dichroism in single chiral nanostructures. The helical dichroism by monochromatic vortex beams can unambiguously distinguish the intrinsic chirality of nanostructures, in an excellent agreement with theoretical predictions. The single planar-chiral nanostructure can exhibit giant helical dichroism of ∼20% at the visible wavelength. The vortex-dependent helical dichroism, expanding to single nanostructures and two-dimensional space, has implications for high-efficiency chiroptical detection of planar-chiral nanostructures in chiral optics and nanophotonic systems.”

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Publication: ACS Nano
Issue/Year: ACS Nano, Volume 15; Number 2; Pages 2893-2900; 2021
DOI: 10.1021/acsnano.0c08941

Velocity measurements with structured light transmitted through a multimode optical fiber using digital optical phase conjugation

Author(s):

Lars Büttner and Martin Thümmler and Jürgen Czarske

Abstract:

“Lensless fiber microendoscopes enable optical diagnostics and therapy with minimal
invasiveness. Because of their small diameters, multimode fibers are ideal candidates, but mode
scrambling hinders the transmission of structured light fields. We present the generation of a
localized fringe system at variable distances from the distal fiber end by exploiting digital optical
phase conjugation. The replayed fringe system was used for quantitative metrology. Velocity
measurements of a microchannel flow in the immediate proximity of the fiber end without the
use of any imaging lenses are shown. Lensless multimode fiber systems are of interest especially
for biomedical imaging and stimulation as well as technical inspection and flow measurements. ”

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Publication: Optics Express
Issue/Year: Vol. 28, Issue 6, pp. 8064-8075
DOI: 10.1364/OE.386047

Encoding of arbitrary micrometric complex illumination patterns with reduced speckle

Author(s):

Miguel Carbonell-Leal, Gladys Mínguez-Vega, Jesús Lancis, and Omel Mendoza-Yero

Abstract:

“In nonlinear microscopy, phase-only spatial light modulators (SLMs) allow achieving simultaneous two-photon excitation and fluorescence emission from specific region-of-interests (ROIs). However, as iterative Fourier transform algorithms (IFTAs) can only approximate the illumination of selected ROIs, both image formation and/or signal acquisition can be largely affected by the spatial irregularities of the illumination patterns and the speckle noise. To overcome these limitations, we propose an alternative complex illumination method (CIM) able to generate simultaneous excitation of large-area ROIs with full control over the amplitude and phase of light and reduced speckle. As a proof-of-concept we experimentally demonstrate single-photon and second harmonic generation (SHG) with structured illumination over large-area ROIs.”

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Publication: Optics Express
Issue/Year: Vol. 27, Issue 14, pp. 19788-19801 (2019)
DOI: 10.1364/OE.27.019788

Endogenous SHG and 2PEF coherence imaging of substructures in neurons in 3D

Author(s):

Carlos Macias-Romero, Claire Teulon, Marie Didier, and Sylvie Roke

Abstract:

“Neuronal morphology, long-distance transport and signalling critically depend on the organization of microtubules in the cytoskeleton. Second harmonic generation (SHG) imaging has been recognized as a potentially powerful tool for in situ label-free neuroimaging with specific sensitivity to microtubules. We study here the structural organization of microtubules in living neurons using a wide-field multiphoton microscope that performs 3D imaging using a structured illumination. This microscope allows label-free high throughput imaging of living mammalian neurons. We show that we can image structural correlations by taking advantage of the structured illumination and the coherence of the emitted light. The result allows us to study the microtubule organization throughout the development of the neuron and to differentiate between the regions of the cytoskeleton in the matured neuron.”

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Publication: Optics Express
Issue/Year: Vol. 27, Issue 3, pp. 2235-2247 (2019)
DOI: 10.1364/OE.27.002235

Raman imaging through multimode sapphire fiber

Author(s):

Sunan Deng, Damien Loterie, Georgia Konstantinou, Demetri Psaltis, and Christophe Moser
Abstract:

“We report on a sapphire fiber Raman imaging probe’s use for challenging applications where access is severely restricted. Small-dimension Raman probes have been developed previously for various clinical applications because they show great capability for diagnosing disease states in bodily fluids, cells, and tissues. However, applications of these sub-millimeter diameter Raman probes were constrained by two factors: first, it is difficult to incorporate filters and focusing optics at such small scale; second, the weak Raman signal is often obscured by strong background noise from the fiber probe material, especially the most commonly used silica, which has a strong broad background noise in low wavenumbers (<500-1700 cm−1). Here, we demonstrate the thinnest-known imaging Raman probe with a 60 μm diameter Sapphire multimode fiber in which both excitation and signal collection pass through. This probe takes advantage of the low fluorescence and narrow Raman peaks of Sapphire, its inherent high temperature and corrosion resistance, and large numerical aperture (NA). Raman images of Polystyrene beads, carbon nanotubes, and CaSO4 agglomerations are obtained with a spatial resolution of 1 μm and a field of view of 30 μm. Our imaging results show that single polystyrene bead (~15 µm diameter) can be differentiated from a mixture with CaSO4 agglomerations, which has a close Raman shift.”

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Publication: Optics Express
Issue/Year: Vol. 27, Issue 2, pp. 1090-1098 (2019)
DOI: 10.1364/OE.27.001090

Aberration correction for improving the image quality in STED microscopy using the genetic algorithm

Author(s):

Luwei Wang, Wei Yan, Runze Li, Xiaoyu Weng, Jia Zhang, Zhigang Yang, Liwei Liu, Tong Ye and Junle Qu

Abstract:

“With a purely optical modulation of fluorescent behaviors, stimulated emission depletion (STED) microscopy allows for far-field imaging with a diffraction-unlimited resolution in theory. The performance of STED microscopy is affected by many factors, of which aberrations induced by the optical system and biological samples can distort the wave front of the depletion beam at the focal plane to greatly deteriorate the spatial resolution and the image contrast. Therefore, aberration correction is imperative for STED imaging, especially for imaging thick specimens. Here, we present a wave front compensation approach based on the genetic algorithm (GA) to restore the distorted laser wave front for improving the quality of STED images. After performing aberration correction on two types of zebrafish samples, the signal intensity and the imaging resolution of STED images were both improved, where the thicknesses were 24 μm and 100 μm in the zebrafish retina sample and the zebrafish embryo sample, respectively. The results showed that the GA-based wave front compensation approach has the capability of correction for both system-induced and sample-induced aberrations. The elimination of aberrations can prompt STED imaging in deep tissues; therefore, STED microscopy can be expected to play an increasingly important role in super-resolution imaging related to the scientific research in biological fields.”

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Publication: Nanophotonics Volume 7: Issue 12
Issue/Year: Volume 7: Issue 12
DOI: 10.1515/nanoph-2018-0133

Nonlinear generation of Airy vortex beam

Author(s):
Hui Li and Haigang Liu and Xianfeng Chen

Abstract:

“Recently, hybrid beams have sparked considerable interest because of their properties coming from different kinds of beams at the same time. Here, we experimentally demonstrate Airy vortex beam generation in the nonlinear frequency conversion process when the fundamental wave with its phase modulated by a spatial light modulator is incident into a homogeneous nonlinear medium. In our experiments, second harmonic Airy circle vortex beams and Airy ellipse vortex beams were generated and the topological charge was also measured. The parabolic trajectory of those Airy vortex beams can be easily adjusted by altering the fundamental wave phase. This study provides a simple way to generate second harmonic Airy vortex beams, which may broaden its future use in optical manipulation and light-sheet microscopy.”

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Publication: Optics Express
Issue/Year: Optics Express Volume 26, Issue 16
DOI: 10.1364/oe.26.021204