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Joint estimation of self-mixing interferometry parameters and displacement reconstruction based on local normalization

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APPLIED OPTICS 2021年第8期60卷 2282-2287页

作者： Kim, Jin-Hyok Kim, Chol-Hyon Yun, Tu-Hon Hong, Hui-Sung Ho, Kwang-Myong Kim, Kwang-Ho Kim Chaek Univ Technol Laser Res Lab Seoul South Korea

It is not easy to estimate self-mixing interferometry parameters, namely, the optical feedback factor and the linewidth enhancement factor from the self-mixing signals (SMSs) affected by noise such as speckle. These SMSs call for normalization, which is not only difficult, but also apt to distort the intrinsic information of the signals, thereby resulting in incorrect estimation of the parameters and the displacement reconstruction. In this paper, we present what we believe is a novel normalization method we call "local normalization," which enables more exact and simpler estimation and displacement retrieval compared to previous methods, for it is based on an analytic relation instead of approximation. The method is very noise-proof, and especially speckle-noise-proof as well. The method proposed can be applied to moderate and strong feedback regimes. The simplicity and accuracy of the method will provide a fine tool for a low-cost self-mixing displacement sensor with a high resolution of about 40 nm. (C) 2021 Optical Society of America

关键词： Diode lasers Laser interferometry Optical feedback Phase unwrapping reconstruction algorithms Speckle noise

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Numerical refractive index correction for the stitching procedure in tomographic quantitative phase imaging

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BIOMEDICAL OPTICS EXPRESS 2022年第11期13卷 5709-5720页

作者： Stepien, Piotr Ziemczonok, Michal Kujawinska, Malgorzata Baczewska, Maria Valenti, Luca Cherubini, Alessandro Casirati, Elia Krauze, Wojciech Warsaw Univ Technol Inst Micromech & Photon Ul Sw Boboli 8 PL-02525 Warsaw Poland Univ Milan Dept Pathophysiol & Transplantat Milan Italy Fdn IRCCS Ca Granda Osped Maggiore Policlin Dept Transfus Med & Hematol Milan Italy

Tomographic quantitative phase imaging (QPI) lacks an absolute refractive index value baseline, which poses a problem when large dense objects extending over multiple fields of view are measured volume by volume and stitched together. Some of the measurements lack the natural baseline value that is provided by the mounting medium with a known refractive index. In this work, we discuss the problem of the refractive index (RI) baseline of individual reconstructed volumes that are deprived of access to mounting medium due to the extent of the object. The solution of this problem is provided by establishing the RI offsets based on the overlapping regions. We have proven that the process of finding the offset RI values may be justifiably reduced to the analogous procedure in the 2D baseline correction (2D-BC). Finally, we proposed the enhancement of the state-of-the-art 2D-BC procedure previously introduced in the context of 2D QPI. The processing is validated at the examples of a synthetic dataset and a liver organoid.

关键词： Phase imaging Phase unwrapping reconstruction algorithms Refractive index Three dimensional imaging Wave propagation

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Direct reconstruction of two ultrashort pulses based on non-interferometric frequency-resolved optical gating

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OPTICS EXPRESS 2021年第4期29卷 5166-5178页

作者： Hidalgo-Rojas, Diego Rojas-Aedo, Ricardo Wheatley, Robert Alastair Gence, Loik Seifert, Birger Pontificia Univ Catolica Chile Fac Fis Casilla 306 Santiago 22 Chile Millennium Inst Res Opt MIRO ANID Millennium Sci Initiat Program Concepcion Chile Univ Luxembourg Dept Phys & Mat Sci L-1511 Luxembourg Luxembourg

We describe a non-interferometric ultrashort-pulse measurement technique based on frequency-resolved optical gating (FROG) with which pulses can be reconstructed directly, i.e. non-iteratively. Two different FROG spectrograms are measured, which represent the only information required to reconstruct the amplitudes and phases of two independent input pulses. The direct reconstruction method is demonstrated with a single-shot FROG setup used to obtain the spectrograms generated from two synchronized input pulses. To demonstrate and determine the reconstruction quality for complex pulses, a programmable pulse shaper is used to modify the pulses sourced from a Kerr-lens mode-locked Ti:sapphire oscillator. (C) 2021 Optical Society of America under the terms of the OSA Open Access Publishing Agreement

关键词： Femtosecond pulse shaping Image reconstruction Optical components reconstruction algorithms Signal processing Ultrashort pulses

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Spk2ImgMamba: Spiking Camera Image reconstruction with Multi-Scale State Space Models

Spk2ImgMamba: Spiking Camera Image Reconstruction with Multi...

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IEEE Workshop on Applications of Computer Vision (WACV)

作者： Jiaoyang Yin Bin Fan Chao Xu Tiejun Huang Boxin Shi State Key Lab of Multimedia Info. Processing School of Computer Science Peking University Nat'l Eng. Research Ctr. of Visual Technology School of Computer Science Peking University Nat'l Key Lab of General AI School of Intelligence Science and Technology Peking University

ISBN: (数字)9798331510831

ISBN: (纸本)9798331510848

As a bio-inspired vision sensor, the spiking camera has showcased remarkable capability in high-speed imaging with a sampling rate of 40,000 Hz. Reconstructing clear images from continuous spike streams, which is obtained by each photosensor continuously detecting photons and firing them asynchronously, has garnered significant attention. Despite promising results, existing spike-to-image reconstruction methods face challenges in balancing global receptive fields and efficient computation due to the inherent limitations of their backbones. Recently, due to powerful long-range modeling and linear complexity, the state space model (SSM) has emerged as a competitive alternative to CNNs and Transformers. In this paper, we propose a lightweight spike-to-image reconstruction network that harnesses Mamba as the backbone. Our approach sequentially executes three core modules: temporal information integration, spatial feature enhancement, and progressive image reconstruction. The former accumulates cues across diverse temporal windows to explore both long-term and short-term contexts. Subsequently, to model global dependencies while heightening local detail perception, we develop a multi-scale SSM block characterized by multi-scale multi-direction scanning, which effectively boosts spatial feature representations. Finally, intensity images are decoded progressively from the enhanced light-intensity features. Extensive experiments on both synthetic and real-captured data demonstrate that our approach achieves state-of-the-art performance, with only 10% of the network parameters and nearly two orders of magnitude less computational effort. The code will be available at https://***/interstellarH/Spk2ImgMamba.

关键词： Correlation Computational modeling reconstruction algorithms Vision sensors Transformer cores Streaming media Cameras Transformers Image reconstruction Streams

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Robust structured light field depth estimation via spinning line operator

Robust structured light field depth estimation via spinning ...

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2024 International Conference on Optical and Photonic Engineering, icOPEN 2024

作者： Guo, Wenfeng Wu, Qingyang Zou, Yifeng Shenzhen Technology University 3002 Lantian Road Pingshan District Shenzhen Guangdong China

ISBN: (数字)9781510688117

ISBN: (纸本)9781510688100

Light fields can simultaneously capture the intensity and direction of each light ray, offering enhanced information for depth estimation. Currently, accurately extracting the epipolar plane lines and handling occlusion are the tough problems of the epipolar plane image depth estimation for light field. Passive depth estimation algorithms only relying on texture information from reconstructed object surfaces struggle to reconstruct texture-free areas, and exhibit poor noise resilience and low accuracy. To address these problems, this paper introduces structured light projection to add accurate and stable texture information, thereby improving the measurement accuracy and robustness, and proposes an epipolar plane line extraction algorithm suitable for structured light field data. This paper designs a spinning line operator based on Structured Light Field characteristics, and uses the variance of the points on the epipolar plane line as the cost of measuring the extraction accuracy. It judges and handles the occlusion problem by gradually removing abnormal points to make the variance converge. This paper measures and reconstructs objects such as standard blocks, standard balls, and portraits, and achieves satisfactory reconstruction results. © 2025 SPIE.

关键词： Structured light reconstruction algorithms Interpolation Cameras Image compression Optical spheres Chaos Image analysis Shadows Spatial resolution

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Fourier ptychographic reconstruction based on an augmented Lagrangian method and sparse approximations for phase and magnitude

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APPLIED OPTICS 2021年第9期60卷 2471-2482页

作者： Chen, Xin Cheng, Haobo Wen, Yongfu Feng, Yunpeng Beijing Inst Technol Sch Opt & Photon Joint Res Ctr Optomechatron Engn Beijing 10081 Peoples R China Beijing Inst Technol Shenzhen Res Inst Shenzhen 518057 Peoples R China

Fourier ptychography microscopy provides a large field of view and high-resolution imaging by simultaneously recovering intensity and phase distributions. However, in real setups, the process of capturing large numbers of low-resolution images will inevitably suffer from imaging noise, which could seriously distort the results recovered using the conventional Fourier ptychography approach. To suppress the effects of imaging noise optimally, a novel, to the best of our knowledge, iterative algorithm is proposed. This algorithm consists of two objective functions;one is based on the augmented Lagrangian function for the inverse computation, and its solution is found by utilizing the alternating direction multiplier method;the other is the separate sparse model built for amplitude and absolute phase image;the filtering process is accomplished by exploiting the block-matching 3D frames. In combination with the Nash equilibrium balancing theory, the proposed algorithm is realized by alternately optimizing the two objective functions. The simulated and experimental results demonstrate that the proposed algorithm is robust to noise and is capable of reconstructing complete and good contrast amplitude and phase images. (C) 2021 Optical Society of America

关键词： Diffraction limit Image processing Image quality Imaging noise Phase retrieval reconstruction algorithms

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reconstruction of atomic resonances with attosecond streaking

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OPTICS EXPRESS 2021年第7期29卷 9711-9722页

作者： Borrego-Varillas, Rocio Lucchini, Matteo IFN CNR Inst Photon & Nanotechnol I-20133 Milan Italy Politecn Milan Dept Phys I-20133 Milan Italy

Recent development of spectroscopic techniques based on attosecond radiation has given the community the right tools to study the timing of the photoelectron process. In this work we investigate the effect of Fano resonances in attosecond streaking spectrograms and the application of standard phase-reconstruction algorithms. We show that while the existence of the infrared coupling (ac-Stark shift) hinders the applicability of FROG-like methods, under certain conditions it is still possible to use standard reconstruction algorithms to retrieve the photoemission delay of the bare resonance. Finally, we propose two strategies to study the strength of IR coupling using the attosecond streaking technique. (C) 2021 Optical Society of America under the terms of the OSA Open Access Publishing Agreement

关键词： Attosecond pulses Fano resonance Fundamental processes Phase retrieval Photoelectron spectra reconstruction algorithms

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Image reconstruction approach for a high space-bandwidth product structured illumination microscopy system

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JOURNAL OF THE OPTICAL SOCIETY OF AMERICA A-OPTICS IMAGE SCIENCE AND VISION 2021年第12期38卷 1744-1751页

作者： Samanta, Krishnendu Joseph, Joby Indian Inst Technol Delhi Dept Phys New Delhi 110016 India

Conventional structured illumination microscopy (SIM) utilizes a sinusoidal excitation pattern of frequency within the detection passband and provides a maximum of twofold resolution enhancement over the diffraction limit. A transmission approach proposed in an earlier publication [J. Phys. D 53, 044006 (2019)] to further improve the lateral resolution requires sequential higher frequency illumination patterns. However, the existing reconstruction algorithms fail to deliver appropriate reconstruction when the excitation frequency lies far from the passband boundary. Here, we present a correlation-based SIM reconstruction approach for sequential highfrequency illumination patterns even if the pattern frequency lies far from the passband limit. The scheme can be suitably implemented in a variety of custom-built systems where illumination frequency lies beyond the passband support (e.g., non-linear SIM and plasmonic SIM). (c) 2021 Optical Society of America

关键词： Diffraction limit Image quality Image reconstruction Live cell imaging reconstruction algorithms Structured illumination microscopy

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Helical CT reconstruction From Sparse-View Data Through Exploiting the 3D Anatomical Structure Sparsity

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IEEE ACCESS 2021年 9卷 15200-15211页

作者： Wang, Yongbo Chen, Gaofeng Xi, Tao Bian, Zhaoying Zeng, Dong Zaidi, Habib He, Ji Ma, Jianhua Southern Med Univ Sch Biomed Engn Guangzhou 510515 Peoples R China Minist Educ Key Lab Intelligent Comp Med Image Shenyang 110819 Peoples R China Southern Med Univ Guangzhou Key Lab Med Radiat Imaging & Detect Tec Guangzhou 510515 Guangdong Peoples R China South China Univ Technol Coll Automat Sci & Engn Guangzhou 510641 Peoples R China Geneva Univ Hosp Div Nucl Med & Mol Imaging CH-1211 Geneva Switzerland Pazhou Lab Guangzhou 510330 Peoples R China

Sparse-view scanning has great potential for realizing ultra-low-dose computed tomography (CT) examination. However, noise and artifacts in reconstructed images are big obstacles, which must be handled to maintain the diagnosis accuracy. Existing sparse-view CT reconstruction algorithms were usually designed for circular imaging geometry, whereas the helical imaging geometry is commonly adopted in the clinic. In this paper, we show that the sparse-view helical CT (SHCT) images contain not only noise and artifacts but also severe anatomical distortions. These troubles reduce the applicability of existing sparse-view CT reconstruction algorithms. To deal with this problem, we analyzed the three-dimensional (3D) anatomical structure sparsity in SHCT images. Based on the analyses, we proposed a tensor decomposition and anisotropic total variation regularization model (TDATV) for SHCT reconstruction. Specifically, the tensor decomposition works on nonlocal cube groups to exploit the anatomical structure redundancy;the anisotropic total variation works on the whole volume to exploit the structural piecewise-smooth. Finally, an alternating direction method of multipliers is developed to solve the TDATV model. To our knowledge, the paper presents the first work investigating the reconstruction of sparse-view helical CT. The TDATV model was validated through digital phantom, physical phantom, and clinical patient studies. The results reveal that SHCT could serve as a potential solution for reducing HCT radiation dose to ultra-low level by using the proposed TDATV model.

关键词： Computed tomography Image reconstruction Geometry Anatomical structure reconstruction algorithms Imaging Three-dimensional displays Helical CT sparse-view tensor total variation iterative reconstruction

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High-fidelity optical diffraction tomography of live organisms using iodixanol refractive index matching

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BIOMEDICAL OPTICS EXPRESS 2022年第12期13卷 6404-6415页

作者： Lee, Dohyeon Lee, Moosung Kwak, Haechan Kim, Young seo Shim, Jaehyu Jung, Jik Han Park, Wei - sun Park, Ji -ho Lee, Sumin Park, Yongkeun Korea Adv Inst Sci & Technol KAIST Dept Phys Daejeon 34141 South Korea Korea Adv Inst Sci & Technol KAIST Inst Hlth Sci & Technol Daejeon 34141 South Korea Korea Adv Inst Sci & Technol Dept Bio & Brain Engn Daejeon 34141 South Korea Tomocube Inc Daejeon 34109 South Korea

Optical diffraction tomography (ODT) enables the three-dimensional (3D) refractive index (RI) reconstruction. However, when the RI difference between a sample and a medium increases, the effects of light scattering become significant, preventing the acquisition of high-quality and accurate RI reconstructions. Herein, we present a method for high-fidelity ODT by introducing non-toxic RI matching media. Optimally reducing the RI contrast enhances the fidelity and accuracy of 3D RI reconstruction, enabling visualization of the morphology and intra-organization of live biological samples without producing toxic effects. We validate our method using various biological organisms, including C. albicans and C. elegans.(c) 2022 Optica Publishing Group under the terms of the Optica Open Access Publishing Agreement

关键词： Digital micromirror devices Image quality Light scattering Multiple scattering reconstruction algorithms Three dimensional reconstruction

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