Binary phase masks for easy system alignment and basic aberration sensing with spatial light modulators in STED microscopy

Author(s):

Klauss, André and Conrad, Florian and Hille, Carsten Hille

Abstract:

“The use of binary phase patterns to improve the integration and optimization of spatial light modulators (SLM) in an imaging system, especially a confocal microscope, is proposed and demonstrated. The phase masks were designed to create point spread functions (PSF), which exhibit specific sensitivity to major disturbances in the optical system. This allows direct evaluation of misalignment and fundamental aberration modes by simple visual inspection of the focal intensity distribution or by monitoring the central intensity of the PSF. The use of proposed phase masks is investigated in mathematical modelling and experiment for the use in a stimulated emission depletion (STED) microscope applying wavefront shaping by a SLM. We demonstrate the applicability of these phase masks for modal wavefront sensing of low order aberration modes up to the third order of Zernike polynomials, utilizing the point detector of a confocal microscope in a ‘guide star’ approach. A lateral resolution of ~25 nm is shown in STED imaging of the confocal microscope retrofitted with a SLM and a STED laser and binary phase mask based system optimization.”

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Publication: Scientific Reports
Issue/Year/DOI: Scientific Reports Volume 7, Article number: 15699 (2017)
DOI: 10.1038/s41598-017-15967-5

Silver Nanowires for Reconfigurable Bloch Surface Waves.

Author(s):

Zhang, Douguo and Wang, Ruxue and Xiang, Yifeng and Kuai, Yan and Kuang, Cuifang and Badugu, Ramachandram and Xu, Yingke and Wang, Pei and Ming, Hai and Liu, Xu and Lakowicz, Joseph R.

Abstract:

“The use of a single silver nanowire as a flexible coupler to transform a free space beam into a Bloch surface wave propagating on a dielectric multilayer is proposed. Based on Huygens ‘Principle, when a Gaussian beam is focused onto a straight silver nanowire, a Bloch surface wave is generated and propagates perpendicular to the nanowire. By curving the silver nanowire, the surface wave can be focused. Furthermore, the spatial phase of the incident laser beam can be actively controlled with the aid of a spatial light modulator, resulting in the reconfigurable or dynamically controlled Bloch surface waves. The low cost of the chemically synthesized silver nanowires and the high flexibility with regard to tuning the spatial phase of the incident light make this approach very promising for various applications including optical micromanipulation, fluorescence imaging, and sensing.”

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Publication: ACS Nano

Issue/Year/DOI:  ACS Nano, 2017, 11 (10), pp 10446–10451
DOI: 10.1021/acsnano.7b05638

Precise spatio-temporal control of rapid optogenetic cell ablation with mem-KillerRed in Zebrafish.

Author(s):

Buckley, C. and Carvalho, M. T. and Young, L. K. and Rider, S. A. and McFadden, C. and Berlage, C. and Verdon, R. F. and Taylor, J. M. and Girkin, J. M. and Mullins, J. J.

Abstract:

“The ability to kill individual or groups of cells in vivo is important for studying cellular processes and their physiological function. Cell-specific genetically encoded photosensitizing proteins, such as KillerRed, permit spatiotemporal optogenetic ablation with low-power laser light. We report dramatically improved resolution and speed of cell targeting in the zebrafish kidney through the use of a selective plane illumination microscope (SPIM). Furthermore, through the novel incorporation of a Bessel beam into the SPIM imaging arm, we were able to improve on targeting speed and precision. The low diffraction of the Bessel beam coupled with the ability to tightly focus it through a high NA lens allowed precise, rapid targeting of subsets of cells at anatomical depth in live, developing zebrafish kidneys. We demonstrate that these specific targeting strategies significantly increase the speed of optoablation as well as fish survival.”

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Publication: Scientific Reports

Issue/Year/DOI: Scientific Reports, volume 7, Article number: 5096 (2017)
DOI: 10.1038/s41598-017-05028-2

Coherent optical adaptive technique improves the spatial resolution of STED microscopy in thick samples

Author(s):

Wei Yan and Yanlong Yang and Yu Tan and Xun Chen and Yang Li and Junle Qu and Tong Ye

Abstract:

“Stimulated emission depletion (STED) microscopy is one of far-field optical microscopy techniques that can provide sub-diffraction spatial resolution. The spatial resolution of the STED microscopy is determined by the specially engineered beam profile of the depletion beam and its power. However, the beam profile of the depletion beam may be distorted due to aberrations of optical systems and inhomogeneity of a specimen’s optical properties, resulting in a compromised spatial resolution. The situation gets deteriorated when thick samples are imaged. In the worst case, the severe distortion of the depletion beam profile may cause complete loss of the super-resolution effect no matter how much depletion power is applied to specimens. Previously several adaptive optics approaches have been explored to compensate aberrations of systems and specimens. However, it is difficult to correct the complicated high-order optical aberrations of specimens. In this report, we demonstrate that the complicated distorted wavefront from a thick phantom sample can be measured by using the coherent optical adaptive technique. The full correction can effectively maintain and improve spatial resolution in imaging thick samples.”

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Publication: Photonics Research

Issue/Year/DOI: Photonics Research, Vol. 5, Issue3, pp. 176-181 (2017)
DOI: 10.1364/PRJ.5.000176

New microscopy technique based on position localization of scattering particles

Author(s):

Stefano Luigi Oscurato and Fabio Borbone and Robert Charles Devlin and Federico Capasso and Pasqualino Maddalena and Antonio Ambrosio

Abstract:

“We introduce the Holographic – Single Scatterer Localization Microscopy in which we combine dynamical laser speckle illumination with centroid localization of backscattered light spots in order to localize isolated scattering particles. The reconstructed centroid images show very accurate particle localization, with precision much better than the width of diffraction-limited image of the particles recorded by the CCD. Furthermore, the method provides an improved resolution in distinguishing two very close scattering objects compared to the standard laser scanning techniques and can be assimilated to a confocal technique in the ability of light background rejection in three-dimensional disposition of scattering objects. The illumination is controlled via a digital holography setup based on the use of a spatial light modulator. This allows not only a high level of versatility in the illumination patterns, but also the remarkable characteristics of absence of moving mechanical parts, typical of the laser scanning techniques, and the possibility of strongly miniaturizing the setup.”

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Publication: Optics Express

Issue/Year/DOI: Optics Express Vol. 25, Issue 10, pp. 11530-11549 (2017)

DOI: 10.1364/OE.25.011530

 

Diffraction-free light droplets for axially-resolved volume imaging.

Author(s):

Antonacci, G. and Domenico, G. Di and Silvestri, S. and DelRe, E. and Ruocco, G.

Abstract:

“An ideal direct imaging system entails a method to illuminate on command a single diffraction-limited region in a generally thick and turbid volume. The best approximation to this is the use of large-aperture lenses that focus light into a spot. This strategy fails for regions that are embedded deep into the sample, where diffraction and scattering prevail. Airy beams and Bessel beams are solutions of the Helmholtz Equation that are both non-diffracting and self-healing, features that make them naturally able to outdo the effects of distance into the volume but intrinsically do not allow resolution along the propagation axis. Here, we demonstrate diffraction-free self-healing three-dimensional monochromatic light spots able to penetrate deep into the volume of a sample, resist against deflection in turbid environments, and offer axial resolution comparable to that of Gaussian beams. The fields, formed from coherent mixtures of Bessel beams, manifest a more than ten-fold increase in their undistorted penetration, even in turbid milk solutions, compared to diffraction-limited beams. In a fluorescence imaging scheme, we find a ten-fold increase in image contrast compared to diffraction-limited illuminations, and a constant axial resolution even after four Rayleigh lengths. Results pave the way to new opportunities in three-dimensional microscopy.”

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Publication: Scientific Reports

Issue/Year/DOI: Scientific Reports volume 7, Article number: 17 (2017)
DOI: 10.1038/s41598-017-00042-w

Far-field imaging of non-fluorescent species with subdiffraction resolution

Author(s):

Wang, Pu, and Mikhail N. Slipchenko, and James Mitchell, and Chen Yang, and Eric O. Potma, and Xianfan Xu, and Ji-Xin Cheng

Abstract:

“Super-resolution optical microscopy is providing a new means by which to view as yet unseen details on a nanoscopic scale. Current far-field super-resolution techniques rely on fluorescence as the readout1–5.
Here, we demonstrate a scheme for breaking the diffraction limit in far-field imaging of nonfluorescent species by using spatially controlled saturation of electronic absorption. Our method is based on a pump–probe process where a modulated pump field perturbs the charge carrier density in a sample, thus modulating the transmission of a probe field. A doughnut-shaped laser beam is then added to transiently saturate the electronic transition in the periphery of the focal volume, so the induced modulation in the sequential probe pulse only occurs at the focal centre. By raster-scanning the three collinearly aligned beams, high-speed subdiffractionlimitedimaging of graphite nanoplatelets is performed. This technique has the potential to enable super-resolution imaging of nanomaterials and non-fluorescent chromophores, which may remain out of reach to fluorescence-based methods.”

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Publication: NATURE PHOTONICS ADVANCE ONLINE PUBLICATION

Issue/Year/DOI: Nature Photonics volume 7, pages 449–453 (2013)
DOI: 10.1038/NPHOTON.2013.97

Double peacock eye optical element for extended focal depth imaging with ophthalmic applications

Author(s): Lenny A. Romero, María S. Millán, Zbigniew Jaroszewicz, Andrzej Kolodziejczyk.

Abstract:

“The aged human eye is commonly affected by presbyopia, and therefore, it gradually loses its capability to form images of objects placed at different distances. Extended depth of focus (EDOF) imaging elements can overcome this inability, despite the introduction of a certain amount of aberration. This paper evaluates the EDOF imaging performance of the so-called peacock eye phase diffractive element, which focuses an incident plane wave into a segment of the optical axis and explores the element’s potential use for ophthalmic presbyopia compensation optics. Two designs of the element are analyzed: the single peacock eye, which produces one focal segment along the axis, and the double peacock eye, which is a spatially multiplexed element that produces two focal segments with partial overlapping along the axis. The performances of the peacock eye elements are compared with those of multifocal lenses through numerical simulations as well as optical experiments in the image space. The results demonstrate that the peacock eye elements form sharper images along the focal segment than the multifocal lenses and, therefore, are more suitable for presbyopia compensation. The extreme points of the depth of field in the object space, which represent the remote and the near object points, have been experimentally obtained for both the single and the double peacock eye optical elements. The double peacock eye element has better imaging quality for relatively short and intermediate distances than the single peacock eye, whereas the latter seems better for far distance vision.”

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Publication: Journal of Biomedical Optics , (subscription required)

Issue/Year/DOI: J. Biomed. Opt. 17, 046013 (Apr 27, 2012)
doi:10.1117/1.JBO.17.4.046013

Light-induced spiral mass transport in azo-polymer films under vortex-beam illumination

Author(s): Antonio Ambrosio, Lorenzo Marrucci, Fabio Borbone, Antonio Roviello, Pasqualino Maddalena

Abstract:

“When an azobenzene-containing polymer film is exposed to a non-uniform illumination, a light-induced mass migration process may be induced, leading to the formation of relief patterns on the polymer free surface. Despite a research effort of many years and several proposed models many aspects of this phenomenon remain not well understood. Here we report the appearance of spiral-shaped relief patterns on the polymer under the illumination of focused Laguerre-Gauss beams, having helical wavefront and an optical vortex at their axis. The induced spiral reliefs are sensitive to the vortex topological charge and to the wavefront handedness. These findings are unexpected, because the “doughnut”-shaped intensity profile of Laguerre- Gauss beams contains no information about the wavefront handedness. We propose a model that explains the main features of this phenomenon from the surface-mediated interference of the longitudinal and the transverse components of the optical field. These results may find applications in optical micro- and nanolithography and optical-field. ”

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Publication: eprint arXiv:1203.5205, (free download)

Issue/Year/DOI: eprint arXiv:1203.5205 (2012)
Bibliographic Code: 2012arXiv1203.5205A

Three dimensional optical twisters-driven helically stacked multi-layered microrotors

Author(s): Jolly Xavier, Raktim Dasgupta, Sunita Ahlawat, Joby Joseph, and Pradeep Kumar Gupta

Abstract:

“We demonstrate tunable helically stacked multi-layered microrotors realized in vortex-embedded three dimensional (3D) optical twister patterns. Intensity-tunable annular irradiance profiles with higher order vortex are generated as well as simultaneously unfolded by phase-engineered multiple plane wave interference. In the individually tunable 3D helical bright arms of these unfolded vortex structures, 2 μm silica beads are optically trapped as spiraling multilayered handles of multi-armed microrotors. Further, multiple rows of such microrotors are parallelly actuated with controllable sense of rotation. We also present our observation on helical 3D stacking of micro-particles in these longitudinally gyrating multi-armed rotor traps.”

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Publication: Applied Physics Letters, (subscription required)

Issue/Year/DOI: Applied Physics Letters, Volume 100, Issue 12, (2012)
doi:10.1063/1.3693413