Distortion correction for wide angle holographic projector

Author(s):

Jędrzej Szpygiel, Maksymilian Chlipała, Rafał Kukołowicz, Moncy Idicula, Tomasz Kozacki

Abstract:

“This letter presents a distortion correction method enabling a distortion minimized, large size image in a wide angle holographic projector. The technique applies numerical predistortion of an input image used for hologram generation. It is based on estimation of distortion coefficients by comparing optically a reconstructed point test chart with the original one. Obtained experimental results prove that the technique allows reconstruction of high-quality image.”

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Publication: Photonics Letters of Poland
Issue/Year: Photonics Letters of Poland, Volume 13; Number 4; Pages 79; 2021
DOI: 10.4302/plp.v13i4.1125

Coded aperture correlation holography (COACH) with a superior lateral resolution of FINCH and axial resolution of conventional direct imaging systems

Author(s):

Bulbul, Angika; Hai, Nathaniel & Rosen, Joseph

Abstract:

“Fresnel incoherent correlation holography (FINCH) is a self-interference incoherent digital holography technique. It possesses a higher lateral resolution than an equivalent incoherent imaging system. However, FINCH has lower axial resolution than the direct imaging systems with the same numerical aperture. A decade after the FINCH invention, a different incoherent holographic method named coded aperture correlation holography (COACH) was developed with improved axial resolution but with the same lateral resolution as direct imaging. In this study, we propose and demonstrate a variant of COACH called coded aperture with FINCH intensity responses (CAFIR) with an improved lateral resolution that is similar to the FINCH system while maintaining its high axial resolution similar to the direct imaging system. CAFIR is implemented with coded phase masks to generate an ensemble of quasi-randomly distributed FINCH-like responses. Point spread holograms and object holograms are recorded under identical conditions, and they are cross-correlated to obtain the image reconstruction. Imaging of a multiplane object is studied to compare the axial resolution of CAFIR with FINCH and direct imaging systems.”

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Publication: Optics Express
Issue/Year: Optics Express, Volume 29; Number 25; Pages 42106; 2021
DOI: 10.1364/oe.446945

Complex-amplitude single-pixel imaging using coherent structured illumination

Author(s):

Hou, Hong-Yun; Zhao, Ya-Nan; Han, Jia-Cheng; Cui, Sheng-Wei; Cao, De-Zhong; Liu, Hong-Chao; Zhang, Su-Heng & Liang, Bao-Lai

Abstract:

“This research presents a coherent structured illumination single-pixel imaging scheme to image objects with complex amplitudes. By utilizing a phase-only spatial light modulator for phase modulation, we can efficiently generate the Hadamard basis structured light and the reference light that interfere with each other to form the coherent structured illumination. Using the 4-step phase-shifting, the spectrum of the object is acquired by detecting the zero-frequency component of the object light with a single-pixel photodetector. The desired complex-amplitude image can be further retrieved by applying an inverse Hadamard transform. The proposed scheme is experimentally demonstrated by imaging two etched glass objects, a dragonfly wing, and a resolution test chart. Benefiting from the phase modulation, this scheme has a high efficiency, a high imaging quality, a high spatial resolution, and a simple and stable configuration to obtain both the phase and amplitude information of the target object. The proposed scheme provides a promising complex-amplitude imaging modality with single-pixel detection. Thus it might find broad applications in optical metrology and biomedical science.”

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Publication: Optics Express
Issue/Year: Optics Express, Volume 29; Number 25; Pages 41827; 2021
DOI: 10.1364/oe.443258

Clustering-based CLEAN algorithm in ghost imaging with sparse spatial frequencies

Author(s):

Chang, Chen; Wu, Guohua; Yang, Dongyue; Yin, Longfei & Luo, Bin

Abstract:

“When insufficient samples in the spatial frequency domain could be effectively compensated by the modified CLEAN algorithm, a novel aperture-synthetic scheme of ghost imaging takes advantage of a superior speed of modulation and an enhancement on the spatial resolution. However, there still exist some imperfections in the modified CLEAN reconstructions, such as the fact that some omitted scatter noise still remains or the object contour may be incomplete. Therefore, we optimize the modified CLEAN algorithm by proposing a density clustering algorithm to overcome these drawbacks and improve the visual quality.”

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Publication: Optics Express
Issue/Year: Optics Express, Volume 29; Number 23; Pages 38841; 2021
DOI: 10.1364/oe.440497

Axial resolution enhancement for planar Airy beam light-sheet microscopy via the complementary beam subtraction method

Author(s):

Liu, Chao; Yu, Xianghua; Bai, Chen; Li, Xing; Zhou, Yuan; Yan, Shaohui; Min, Junwei; Dan, Dan; Li, Runze; Gu, Shuangyu & Yao, Baoli

Abstract:

“Airy beam light-sheet illumination can extend the field of view (FOV) of light-sheet fluorescence microscopy due to the unique propagation properties of non-diffraction and self-acceleration. However, the side lobes create undesirable out-of-focus background, leading to poor axial resolution and low image contrast. Here, we propose an Airy complementary beam subtraction (ACBS) method to improve the axial resolution while keeping the extended FOV. By scanning the optimized designed complementary beam that has two main lobes (TML), the generated complementary light-sheet has almost identical intensity distribution to that of the planar Airy light-sheet except for the central lobe. Subtraction of the two images acquired by double exposure respectively using the planar Airy light-sheet and the planar TML light-sheet can effectively suppress the influence of the out-of-focus background. The axial resolution improves from ∼4µm to 1.2 µm. The imaging performance was demonstrated by imaging specimens of aspergillus conidiophores and GFP labeled mouse brain section. The results show that the ACBS method enables the Airy beam light-sheet fluorescence microscopy to obtain better imaging quality.”

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Publication: Applied Optics
Issue/Year: Applied Optics, Volume 60; Number 32; Pages 10239; 2021
DOI: 10.1364/ao.441070

Unfiltered holography: optimizing high diffraction orders without optical filtering for compact holographic displays

Author(s):

Gopakumar, Manu; Kim, Jonghyun; Choi, Suyeon; Peng, Yifan & Wetzstein, Gordon

Abstract:

“Computer-generated holography suffers from high diffraction orders (HDOs) created from pixelated spatial light modulators, which must be optically filtered using bulky optics. Here, we develop an algorithmic framework for optimizing HDOs without optical filtering to enable compact holographic displays. We devise a wave propagation model of HDOs and use it to optimize phase patterns, which allows HDOs to contribute to forming the image instead of creating artifacts. The proposed method significantly outperforms previous algorithms in an unfiltered holographic display prototype.”

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Publication: Optics Letters
Issue/Year: Optics Letters, Volume 46; Number 23; Pages 5822; 2021
DOI: 10.1364/ol.442851

Towards non-blind optical tweezing by finding 3D refractive index changes through off-focus interferometric tracking

Author(s):

Landenberger, Benjamin; Yatish & Rohrbach, Alexander

Abstract:

“In modern 3D microscopy, holding and orienting arbitrary biological objects with optical forces instead of using coverslips and gel cylinders is still a vision. Although optical trapping forces are strong enough and related photodamage is acceptable, the precise (re-) orientation of large specimen with multiple optical traps is difficult, since they grab blindly at the object and often slip off. Here, we present an approach to localize and track regions with increased refractive index using several holographic optical traps with a single camera in an off-focus position. We estimate the 3D grabbing positions around several trapping foci in parallel through analysis of the beam deformations, which are continuously measured by defocused camera images of cellular structures inside cell clusters. Although non-blind optical trapping is still a vision, this is an important step towards fully computer-controlled orientation and feature-optimized laser scanning of sub-mm sized biological specimen for future 3D light microscopy.”

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Publication: Nature Communications
Issue/Year: Nature Communications, Volume 12; Number 1; 2021
DOI: 10.1038/s41467-021-27262-z

Suppression of spurious image duplicates in Fourier holograms by pixel apodization of a spatial light modulator

Author(s):

Joanna Starobrat, Szymon Fiderkiewicz, Andrzej Kołodziejczyk, Maciej Sypek, Romuald Beck, Krystian Pavłov, Mateusz Słowikowski, Adam Kowalczyk, Jarosław Suszek, Michał Makowski

Abstract:

“Holographic projectors and near-eye displays are a promising technology with truly three-dimensional, natural viewing and excellent energetic efficiency. Spatial light modulators with periodic pixel matrices cause image duplicates, which distract the viewer and waste energy of the playback beam. We present the engineering of the far field intensity envelope, which suppresses higher-order image duplicates in the simplest possible optical setup by physically changing the shape of modulator pixels with attached apodizing masks. Numerical and experimental results show the limited number of perceived duplicates and better uniformity in off-axis projections for the price of compromised energetic efficiency due to amplitude masks.”

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Publication: Optics Express
Issue/Year: Optics Express, Volume 29; Number 24; Pages 40259; 2021
DOI: 10.1364/oe.441489

Metamachines of pluripotent colloids

Author(s):

Aubret, Antoine; Martinet, Quentin & Palacci, Jeremie

Abstract:

“Machines enabled the Industrial Revolution and are central to modern technological progress: A machine’s parts transmit forces, motion, and energy to one another in a predetermined manner. Today’s engineering frontier, building artificial micromachines that emulate the biological machinery of living organisms, requires faithful assembly and energy consumption at the microscale. Here, we demonstrate the programmable assembly of active particles into autonomous metamachines using optical templates. Metamachines, or machines made of machines, are stable, mobile and autonomous architectures, whose dynamics stems from the geometry. We use the interplay between anisotropic force generation of the active colloids with the control of their orientation by local geometry. This allows autonomous reprogramming of active particles of the metamachines to achieve multiple functions. It permits the modular assembly of metamachines by fusion, reconfiguration of metamachines and, we anticipate, a shift in focus of self-assembly towards active matter and reprogrammable materials.”

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Publication: Nature Communications
Issue/Year: Nature Communications, Volume 12; Number 1; 2021
DOI: 10.1038/s41467-021-26699-6

Faster generation of holographic video of 3-D scenes with a Fourier spectrum-based NLUT method

Author(s):

Cao, Hongkun; Jin, Xin; Ai, Lingyu & Kim, Eun-Soo

Abstract:

“In this article, a new type of Fourier spectrum-based novel look-up table (FS-NLUT) method is proposed for the faster generation of holographic video of three-dimensional (3-D) scenes. This proposed FS-NLUT method consists of principal frequency spectrums (PFSs) which are much smaller in size than the principal fringe patterns (PFPs) found in the conventional NLUT-based methods. This difference in size allows for the number of basic algebraic operations in the hologram generation process to be reduced significantly. In addition, the fully one-dimensional (1-D) calculation framework of the proposed method also allows for a significant reduction of overall hologram calculation time. In the experiments, the total number of basic algebraic operations needed for the proposed FS-NLUT method were found to be reduced by 81.23% when compared with that of the conventional 1-D NLUT method. In addition, the hologram calculation times of the proposed method, when implemented in the CPU and the GPU, were also found to be 60% and 66% faster than that of the conventional 1-D NLUT method, respectively. It was also confirmed that the proposed method implemented with two GPUs can generate a holographic video of a test 3-D scene in real-time (>24f/s).”

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Publication: Optics Express
Issue/Year: Optics Express, Volume 29; Number 24; Pages 39738; 2021
DOI: 10.1364/oe.442267