25D microscopy with polarization independent SLM for enhanced detection efficiency and aberration correction

Author(s):

Ren, Jinhan & Han, Kyu Young

Abstract:

“Fast, volumetric imaging by fluorescence microscopy is essential in studying bi-ological phenomena and cellular functions. Recently, single-shot 2.5D microscopy showedpromising results for high-throughput quantitative subcellular analysis via extended depth offield imaging without sequentialz-scanning; however, the detection efficiency was limited and itlacked depth-induced aberration correction. Here we report that a spatial light modulator (SLM)in a polarization insensitive configuration can significantly improve the detection efficiency of2.5D microscopy, while also compensating for aberrations at large imaging depths caused bythe refractive index mismatch between the sample and the immersion medium. We highlightthe improved efficiency via quantitative single-molecule RNA imaging of mammalian cellswith a 2-fold improvement in the fluorescence intensity compared to a conventional SLM-basedmicroscopy. We demonstrate the aberration correction capabilities and extended depth of field byimaging thick specimens with fewerz-scanning steps.”

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Publication: Optics Express
Issue/Year: Optics Express, Volume 29; Number 17; Pages 27530; 2021
DOI: 10.1364/oe.434260

Predicting optical transmission through complex scattering media from reflection patterns with deep neural networks

Author(s):

Skarsoulis, Kyriakos; Kakkava, Eirini & Psaltis, Demetri

Abstract:

“Deep neural networks (DNNs) are used to reconstruct transmission speckle intensity patterns from therespective reflection speckle intensity patterns generated by illuminated parafilm layers. The dependence ofthe reconstruction accuracy on the thickness of the sample is examined for different illumination patterns ofvarious feature sizes. High reconstruction accuracy is obtained even for large parafilm thicknesses, for whichthe memory effect of the sample is vanishingly small. The generalization capability of the DNN is also studiedfor unseen scatterers of the same type.”

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Publication: Optics Communications
Issue/Year: Optics Communications, Volume 492; Pages 126968; 2021
DOI: 10.1016/j.optcom.2021.126968

Toward simple, generalizable neural networks with universal training for low-SWaP hybrid vision

Author(s):

Muminov, Baurzhan; Perry, Altai; Hyder, Rakib; Asif, M. Salman & Vuong, Luat T.

Abstract:

“Speed, generalizability, and robustness are fundamental issues for building lightweight computational cameras. Here we demonstrate generalizable image reconstruction with the simplest of hybrid machine vision systems: linear optical preprocessors combined with no-hidden-layer, “small-brain” neural networks. Surprisingly, such simple neural networks are capable of learning the image reconstruction from a range of coded diffraction patterns using two masks. We investigate the possibility of generalized or “universal training” with these small brains. Neural networks trained with sinusoidal or random patterns uniformly distribute errors around a reconstructed image, whereas models trained with a combination of sharp and curved shapes (the phase pattern of optical vortices) reconstruct edges more boldly. We illustrate variable convergence of these simple neural networks and relate learnability of an image to its singular value decomposition entropy of the image. We also provide heuristic experimental results. With thresholding, we achieve robust reconstruction of various disjoint datasets. Our work is favorable for future real-time low size, weight, and power hybrid vision: we reconstruct images on a 15 W laptop CPU with 15,000 frames per second: faster by a factor of 3 than previously reported results and 3 orders of magnitude faster than convolutional neural networks.”

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Publication: Photonics Research
Issue/Year: Photonics Research, Volume 9; Number 7; Pages B253; 2021
DOI: 10.1364/prj.416614

Super-resolution imaging by optical incoherent synthetic aperture with one channel at a time

Author(s):

Bulbul, Angika & Rosen, Joseph

Abstract:

“Imaging with an optical incoherent synthetic aperture (SA) means that the incoherent light from observed objects is processed over time from various points of view to obtain a resolution equivalent to single-shot imaging by the SA larger than the actual physical aperture. The operation of such systems has always been based on two-wave interference where the beams propagate through two separate channels. This limitation of two channels at a time is removed in the present study with the proposed SA where the two beams pass through the same single channel at any given time. The system is based on a newly developed self-interference technique named coded aperture correlation holography. At any given time, the recorded intensity is obtained from interference between two waves co-propagating through the same physical channel. One wave oriented in a particular polarization is modulated by a pseudorandom coded phase mask and the other one oriented orthogonally passes through an open subaperture. Both subapertures are multiplexed at the same physical window. The system is calibrated by a point spread hologram synthesized from the responses of a guide star. All the measurements are digitally processed to achieve a final image with a resolution higher than that obtained by the limited physical aperture. This unique configuration can offer alternatives for the current cumbersome systems composed of far apart optical channels in the large optical astronomical interferometers. Furthermore, the proposed concept paves the way to an SA system with a single less-expensive compact light collector in an incoherent optical regime that may be utilized for future ground-based or space telescopes.”

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Publication: Photonics Research
Issue/Year: Photonics Research, Volume 9; Number 7; Pages 1172; 2021
DOI: 10.1364/prj.422381

DL-SI-DHM: a deep network generating the high-resolution phase and amplitude images from wide-field images

Author(s):

Meng, Zhang; Pedrini, Giancarlo; Lv, Xiaoxu; Ma, Jun; Nie, Shouping & Yuan, Caojin

Abstract:

“Structured illumination digital holographic microscopy (SI-DHM) is a high-resolution, label-free technique enabling us to image unstained biological samples. SI-DHM has high re- quirements on the stability of the experimental setup and needs long exposure time. Furthermore, image synthesizing and phase correcting in the reconstruction process are both challenging tasks. We propose a deep-learning-based method called DL-SI-DHM to improve the recording, the reconstruction efficiency and the accuracy of SI-DHM and to provide high-resolution phase imaging. In the training process, high-resolution amplitude and phase images obtained by phase-shifting SI-DHM together with wide-field amplitudes are used as inputs of DL-SI-DHM. The well-trained network can reconstruct both the high-resolution amplitude and phase images from a single wide-field amplitude image. Compared with the traditional SI-DHM, this method significantly shortens the recording time and simplifies the reconstruction process and complex phase correction, and frequency synthesizing are not required anymore. By comparsion, with other learning-based reconstruction schemes, the proposed network has better response to high frequencies. The possibility of using the proposed method for the investigation of different biological samples has been experimentally verified, and the low-noise characteristics were also proved.”

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Publication: Optics Express
Issue/Year: Optics Express, Volume 29; Number 13; Pages 19247; 2021
DOI: 10.1364/oe.424718

Simplified digital content generation based on an inverse-directed propagation algorithm for holographic stereogram printing

Author(s):

Khuderchuluun, Anar; Piao, Yan-Ling; Erdenebat, Munkh-Uchral; Dashdavaa, Erkhembaatar; Lee, Moung Hee; Jeon, Seok-Hee & Kim, Nam

Abstract:

“Holographic stereogram (HS) printing requires extensive memory capacity and long computation time during perspective acquisition and implementation of the pixel re-arrangement algorithm. Hogels contain very weak depth information of the object. We propose a HS printing system that uses simplified digital content generation based on the inverse-directed propagation (IDP) algorithm for hogel generation. Specifically, the IDP algorithm generates an array of hogels using a simple process that acquires the full three-dimensional (3D) information of the object, including parallax, depth, color, and shading, via a computer-generated integral imaging technique. This technique requires a short computation time and is capable of accounting for occlusion and accommodation effects of the object points via the IDP algorithm. Parallel computing is utilized to produce a high-resolution hologram based on the properties of independent hogels. To demonstrate the proposed approach, optical experiments are conducted in which the natural 3D visualizations of real and virtual objects are printed on holographic material. Experimental results demonstrate the simplified computation involved in content generation using the proposed IDP-based HS printing system and the improved image quality of the holograms.”

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Publication: Applied Optics
Issue/Year: Applied Optics, Volume 60; Number 14; Pages 4235; 2021
DOI: 10.1364/ao.423205

Aberration-free digital holographic phase imaging using the derivative-based principal component analysis

Author(s):

Lai, Xiaomin; Xiao, Sheng; Xu, Chen; Fan, Shanhui & Wei, Kaihua

Abstract:

“Significance: Digital holographic microscopy is widely used to get the quantitative phase information of transparent cells.

Aim: However, the sample phase is superimposed with aberrations. To quantify the phase information, aberrations need to be fully compensated.

Approach: We propose a technique to obtain aberration-free phase imaging, using the derivative-based principal component analysis (dPCA).

Results: With dPCA, almost all aberrations can be extracted and compensated without requirements on background segmentation, making it efficient and convenient.

Conclusions: It solves the problem that the conventional principal component analysis (PCA) algorithm cannot compensate the common but intricate higher order cross-term aberrations, such as astigmatism and coma. Moreover, the dPCA strategy proposed here is not only suitable for aberration compensation but also applicable for other cases where there exist cross-terms that cannot be analyzed with the PCA algorithm.”

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Publication: Journal of Biomedical Optics
Issue/Year: Journal of Biomedical Optics, Volume 26; Number 04; 2021
DOI: 10.1117/1.jbo.26.4.046501

SLM Simulation and MonteCarlo Path Tracing for Computer-Generated Holograms

Author(s):

Magallón, Juan; Blesa, Alfonso & Serón, Francisco

Abstract:

“Computer holography is a growing research field that must pay attention to two main issues concerning computing effort: the visualization of a 3D virtual scene with photo-realistic quality and the bottleneck related to hologram digitizalition and visualization limits. This work shows a computational approach based on a Monte Carlo path-tracing algorithm, which accounts for both geometrical and physical phenomena involved in hologram generation, and, therefore, makes a feasible estimation of computing time costs. As these holograms also require yet unavailable visualization devices, their behavior needs to be simulated by computer techniques.”

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Publication: SN Computer Science
Issue/Year: SN Computer Science, Volume 2; Number 3; 2021
DOI: 10.1007/s42979-021-00632-6

Real-time sub-wavelength imaging of surface waves with nonlinear near-field optical microscopy

Author(s):

Frischwasser, Kobi; Cohen, Kobi; Kher-Alden, Jakob; Dolev, Shimon; Tsesses, Shai & Bartal, Guy

Abstract:

“Imaging evanescent waves is of crucial importance for sub-wavelength-scale investigation of various phenomena. However, frequently used techniques for near-field imaging require either a strong perturbation of the field, long acquisition times or complex electron-based tools. Here, we introduce nonlinear near-field optical microscopy (NNOM), which is capable of real-time evanescent wave imaging by nonlinear wave mixing while using only standard optical components. As a proof-of-concept, we present non-perturbative, single-shot mapping of evanescent plasmonic patterns, utilizing the nonlinearity of the host metal, and monitor in real time the externally controlled changes to the patterns. We further demonstrate the ability to extract the full field information—the amplitude and phase of all electric-field components—in a polarization-sensitive, spin-selective manner. This simple and highly tunable technique could be extended to deep sub-wavelength imaging of polaritons in two-dimensional materials or other nanophotonic guided modes, for swift photonic device characterization and optimized light−matter interactions.”

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Publication: Nature Photonics
Issue/Year: Nature Photonics, Volume 15; Number 6; Pages 442–448; 2021
DOI: 10.1038/s41566-021-00782-2

Holographic contact lens display that provides focusable images for eyes

Author(s):

Sano, Junpei & Takaki, Yasuhiro

Abstract:

“In this paper, we propose a holographic image generation technique for contact lens displays. The proposed technique employs a phase-only spatial light modulator (SLM), a holographic optical element (HOE) backlight, and a polarizer. The proposed holographic technique can generate 3D images apart from the contact lens displays. Therefore, the eyes can focus on the 3D images while simultaneously observing the real scene through the phase-only SLM and the HOE backlight, which provides see-through capability. A bench-top experimental system was constructed to verify the far-distance image generation capability and see-through function.”

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Publication: Optics Express
Issue/Year: Optics Express, Volume 29; Number 7; Pages 10568; 2021
DOI: 10.1364/oe.419604