Generation of Tunable Fractional Vector Curvilinear Beams With Controllable Phase Distribution

Author(s):

Fengyan Gu, Zhongzheng Gu, Chenliang Chang, Caojin Yuan, Shaotong Feng, Fangjian Xing and Shouping Nie

Abstract:

“An approach to generate the tunable fractional vector curvilinear beams (VCBs) was proposed. The scheme is based on the vector optical field generator (VOFG) system, where the two orthogonal polarized scalar curvilinear beams (SCBs) are generated to be the base vector components, and coaxially superposed by a Ronchi grating. We design a new phase distribution with several loops of 0 to π in order to generate more dark gaps. The phase distribution becomes nonuniform by varying the phase variation rate and the positions of the dark gaps are changed. Using the different parameters of the curves, the fractional VCBs with different shapes are achieved. The two orthogonal polarized SCBs with the opposite topological charges are modulated to perform the beam conversion by a phase-only computer-generated hologram (CGH). Our experimental results comply with the theory and the radial opening of the dark gaps may have some applications for guiding and transporting particles.”

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Publication: IEEE Photonics Journal
Issue/Year: Volume: 11 Issue: 6 (2019)
DOI: 10.1109/JPHOT.2019.2942041

High-Speed Large-Field Multifocal Illumination Fluorescence Microscopy

Author(s):

Chen, Zhenyue; Mc Larney, Benedict; Rebling, Johannes; Deán-Ben, Xosé Luis; Zhou, Quanyu; Gottschalk, Sven & Razansky, Daniel

Abstract:

“Abstract Scanning optical microscopy techniques are commonly restricted to a sub-millimeter field-of-view (FOV) or otherwise employ slow mechanical translation, limiting their applicability for imaging fast biological dynamics occurring over large areas. A rapid scanning large-field multifocal illumination (LMI) fluorescence microscopy technique is devised based on a beam-splitting grating and an acousto-optic deflector synchronized with a high-speed camera to attain real-time fluorescence microscopy over a centimeter-scale FOV. Owing to its large depth of focus, the approach allows noninvasive visualization of perfusion across the entire mouse cerebral cortex, not achievable with conventional wide-field fluorescence microscopy methods. The new concept can readily be incorporated into conventional wide-field microscopes to mitigate image blur due to tissue scattering and attain optimal trade-off between spatial resolution and FOV. It further establishes a bridge between conventional wide-field macroscopy and laser scanning confocal microscopy, thus it is anticipated to find broad applicability in functional neuroimaging, in vivo cell tracking, and other applications looking at large-scale fluorescent-based biodynamics.”

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Publication: Laser & Photonics Reviews
Issue/Year: Laser & Photonics Reviews, Volume n/a; Number n/a; Pages 1900070; 2019
DOI: 10.1002/lpor.201900070

Wirtinger holography for near-eye displays

Author(s):

Chakravarthula, Praneeth; Peng, Yifan; Kollin, Joel; Fuchs, Henry & Heide, Felix

Abstract:

“Near-eye displays using holographic projection are emerging as an exciting display approach for virtual and augmented reality at high-resolution without complex optical setups — shifting optical complexity to computation. While precise phase modulation hardware is becoming available, phase retrieval algorithms are still in their infancy, and holographic display approaches resort to heuristic encoding methods or iterative methods relying on various relaxations.
In this work, we depart from such existing approximations and solve the phase retrieval problem for a hologram of a scene at a single depth at a given time by revisiting complex Wirtinger derivatives, also extending our framework to render 3D volumetric scenes. Using Wirtinger derivatives allows us to pose the phase retrieval problem as a quadratic problem which can be minimized with first-order optimization methods. The proposed Wirtinger Holography is flexible and facilitates the use of different loss functions, including learned perceptual losses parametrized by deep neural networks, as well as stochastic optimization methods. We validate this framework by demonstrating holographic reconstructions with an order of magnitude lower error, both in simulation and on an experimental hardware prototype.”

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Publication: ACM Transactions on Graphics (TOG)
Issue/Year: ACM Transactions on Graphics (TOG), Volume 38; Number 6; Pages 213; 2019
DOI: 10.1145/3355089.3356539

Optical sensor based on pseudo-random diffractive optical elements for reliable gesture reconstruction

Author(s):

Ruser, H.; Kaltenbach, A.; Mechold, L.; Obée, F. & Piela, F.

Abstract:

“The concept, design guidelines and reconstruction results for a universal gesture-based optical remote control with simple quasi-intuitive operation are presented. The buttonless hand-held flashlight-type device emits ‘structured’ infrared light with a pseudo-random spatial pattern projected by a diffractive optical element (DOE). A cost-effective array of photodetectors on or near the device to be remotely controlled records the spatio-temporal intensity changes while a gesture is carried out. From the consecutive time lags between highly correlated signal segments received at each pair of photodetectors, the velocity vector is composed from which Cartesian coordinates of the trajectory of motion of the pattern are calculated and the gesture is reconstructed. Extensive simulations varying major design parameters of the DOE pattern and the receiver array were carried out. Based on simulated and typical practical gestures obtained from user tests, design parameters for a highly satisfactory reconstruction performance could be identified.”

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Publication: 2019 IEEE Sensors
Issue/Year: 2019 IEEE Sensors, Pages 1-4; 2019
DOI: 10.1109/SENSORS43011.2019.8956875

Polarization nano-tomography of tightly focused light landscapes by self-assembled monolayers

Author(s):

Eileen Otte, Kemal Tekce, Sebastian Lamping, Bart Jan Ravoo and Cornelia Denz
Abstract:

“Recently, four-dimensional (4D) functional nano-materials have attracted considerable attention due to their impact in cutting-edge fields such as nano-(opto)electronics, -biotechnology or -biomedicine. Prominent optical functionalizations, representing the fourth dimension, require precisely tailored light fields for its optimal implementation. These fields need to be like-wise 4D, i.e., nano-structured in three-dimensional (3D) space while polarization embeds additional longitudinal components. Though a couple of approaches to realize 4D fields have been suggested, their breakthrough is impeded by a lack of appropriate analysis techniques. Combining molecular self-assembly, i.e., nano-chemistry, and nano-optics, we propose a polarization nano-tomography of respective fields using the functional material itself as a sensor. Our method allows a single-shot identification of non-paraxial light fields at nano-scale resolution without any data post-processing. We prove its functionality numerically and experimentally, elucidating its amplitude, phase and 3D polarization sensitivity. We analyze non-paraxial field properties, demonstrating our method’s capability and potential for next generation 4D materials.”

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Publication: Nature Communications
Issue/Year: Nature Communications volume 10, Article number: 4308 (2019)
DOI: 10.1038/s41467-019-12127-3

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

Functional Fluorescence Microscopy Imaging (fFMI). Quantitative Scanning-Free Confocal Fluorescence Microscopy for the Characterization of Fast Dynamic Processes in Live Cells

Author(s):

Krmpot, Aleksandar J.; Nikolić, Stanko N.; Oasa, Sho; Papadopoulos, Dimitrios K.; Vitali, Marco; Oura, Makoto; Mikuni, Shintaro; Thyberg, Per; Tisa, Simone; Kinjo, Masataka; Nilsson, Lennart; Terenius, Lars; Rigler, Rudolf & Vukojevic, Vladana

Abstract:

“Functional fluorescence microscopy imaging (fFMI), a time-resolved (21 μs/frame) confocal fluorescence microscopy imaging technique without scanning, is developed for quantitative characterization of fast reaction-transport processes in solution and in live cells. The method is based on massively parallel fluorescence correlation spectroscopy (FCS). Simultaneous excitation of fluorescent molecules in multiple spots in the focal plane is achieved using a diffractive optical element (DOE). Fluorescence from the DOE-generated 1024 illuminated spots is detected in a confocal arrangement by a matching matrix detector comprising 32 × 32 single-photon avalanche photodiodes (SPADs). Software for data acquisition and fast auto- and cross-correlation analysis by parallel signal processing using a graphic processing unit (GPU) allows temporal autocorrelation across all pixels in the image frame in 4 s and cross-correlation between first- and second-order neighbor pixels in 45 s. We present here this quantitative, time-resolved imaging method with single-molecule sensitivity and demonstrate its usefulness for mapping in live cell location-specific differences in the concentration and translational diffusion of molecules in different subcellular compartments. In particular, we show that molecules without a specific biological function, e.g., the enhanced green fluorescent protein (eGFP), exhibit uniform diffusion. In contrast, molecules that perform specialized biological functions and bind specifically to their molecular targets show location-specific differences in their concentration and diffusion, exemplified here for two transcription factor molecules, the glucocorticoid receptor (GR) before and after nuclear translocation and the Sex combs reduced (Scr) transcription factor in the salivary gland of Drosophila ex vivo.”

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Publication: Analytical Chemistry
Issue/Year: Analytical Chemistry, Volume 91; Number 17; Pages 11129–11137; 2019
DOI: 10.1021/acs.analchem.9b01813

Liquid Crystal Spatial Light Modulator with Optimized Phase Modulation Ranges to Display Multiorder Diffractive Elements

Author(s):

Elisabet Pérez-Cabré; María S. Millán
Abstract:

“A liquid crystal on silicon spatial light modulator (LCoS SLM) with large phase modulation has been thoroughly characterized to operate optimally with several linear phase modulation ranges (π, 2π, 3π, 4π, 6π, and 8π) for an intermediate wavelength of the visible spectrum (λG = 530 nm). For each range, the device response was also measured for two additional wavelengths at the blue and red extremes of the visible spectrum (λB = 476 nm and λR = 647 nm). Multiorder diffractive optical elements, displayed on the LCoS SLM with the appropriate phase modulation range, allowed us to deal with some widely known encoding issues of conventional first-order diffractive lenses such as undersampling and longitudinal chromatic aberration. We designed an achromatic multiorder lens and implemented it experimentally on the SLM. As a result, the residual chromatic aberration reduces to one-third that of the chromatic aberration of a conventional first-order diffractive lens.”

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Publication: Applied Sciences
Issue/Year: Applied Sciences, Volume 9; Number 13; Pages 2592; 2019
DOI: 10.3390/app9132592

DeepSTORM3D: dense three dimensional localization microscopy and point spread function design by deep learning

Author(s):

Nehme, Elias; Freedman, Daniel; Gordon, Racheli; Ferdman, Boris; Weiss, Lucien E.; Alalouf, Onit; Orange, Reut; Michaeli, Tomer & Shechtman, Yoav

Abstract:

“Localization microscopy is an imaging technique in which the positions of individual nanoscale point emitters (e.g. fluorescent molecules) are determined at high precision from their images. This is the key ingredient in single/multiple-particle-tracking and several super-resolution microscopy approaches. Localization in three-dimensions (3D) can be performed by modifying the image that a point-source creates on the camera, namely, the point-spread function (PSF). The PSF is engineered using additional optical elements to vary distinctively with the depth of the point-source. However, localizing multiple adjacent emitters in 3D poses a significant algorithmic challenge, due to the lateral overlap of their PSFs. Here, we train a neural network to receive an image containing densely overlapping PSFs of multiple emitters over a large axial range and output a list of their 3D positions. Furthermore, we then use the network to design the optimal PSF for the multi-emitter case. We demonstrate our approach numerically as well as experimentally by 3D STORM imaging of mitochondria, and volumetric imaging of dozens of fluorescently-labeled telomeres occupying a mammalian nucleus in a single snapshot.”

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Publication: Nature Methods 17
Issue/Year: Nature Methods 17 (2020) 734-740, Volume 17; Number 7; Pages 734–740; 2019
DOI: 10.1038/s41592-020-0853-5
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