检索结果-内蒙古大学图书馆

Spatially-variant image deconvolution for photoacoustic tomography

OPTICS EXPRESS 2023年第13期31卷 21641-21657页

作者： Xie, Dan Dong, Wende Zheng, Jiawei Tian, Chao Univ Sci & Technol China Sch Engn Sci Hefei Anhui Peoples R China Nanjing Univ Aeronaut & Astronaut Coll Automat Engn Nanjing 211106 Jiangsu Peoples R China Hefei Comprehens Natl Sci Ctr Inst Artificial Intelligence Hefei 230088 Anhui Peoples R China

Photoacoustic tomography (PAT) system can reconstruct images of biological tissues with high resolution and contrast. However, in practice, the PAT images are usually degraded by spatially variant blur and streak artifacts due to the non-ideal imaging conditions and chosen reconstruction algorithms. Therefore, in this paper, we propose a two-phase restoration method to progressively improve the image quality. In the first phase, we design a precise device and measuring method to obtain spatially variant point spread function samples at preset positions of the PAT system in image domain, then we adopt principal component analysis and radial basis function interpolation to model the entire spatially variant point spread function. Afterwards, we propose a sparse logarithmic gradient regularized Richardson-Lucy (SLG-RL) algorithm to deblur the reconstructed PAT images. In the second phase, we present a novel method called deringing which is also based on SLG-RL to remove the streak artifacts. Finally, we evaluate our method with simulation, phantom and in vivo experiments, respectively. All the results show that our method can significantly improve the quality of PAT images.

关键词： Biological imaging Image quality Image reconstruction Image resolution Medical imaging reconstruction algorithms

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Data-Driven Input reconstruction and Experimental Validation

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IEEE CONTROL SYSTEMS LETTERS 2022年 6卷 3259-3264页

作者： Shi, Jicheng Lian, Yingzhao Jones, Colin N. Ecole Polytech Fed Lausanne Automat Lab CH-1015 Lausanne Switzerland

This letter proposes a data-driven input reconstruction method from outputs (IRO) based on the Willems' Fundamental Lemma. Given only output measurements, the unknown inputsestimated recursively by the IRO asymptotically converge to the true input without knowing the initial conditions. A recursive IRO and a moving-horizon IRO are developed based respectively on Lyapunov conditions and Luenberger-observer-type feedback, and their asymptotic convergence properties are studied. An experimental study is presented demonstrating the efficacy of the moving-horizon IRO for estimating the occupancy of a building on the EPFL campus via measured carbon dioxide levels.

关键词： Estimation Observers Buildings Standards reconstruction algorithms Matrix decomposition Convergence Input reconstruction data-driven method

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Compressed sensing framework for BCG signals based on the optical fiber sensor

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OPTICS EXPRESS 2023年第18期31卷 29606-29618页

作者： Chen, Shuyang Luo, Huaijian Lyu, Weimin Yu, Jianxun Qin, Jing Yu, Changyuan Hong Kong Polytech Univ Ctr Smart Hlth Sch Nursing Hong Kong Peoples R China Hong Kong Polytech Univ Photon Res Inst Dept Elect & Informat Engn Hong Kong Peoples R China Chinese Univ Hong Kong Dept Comp Sci & Engn Hong Kong Peoples R China

A compressed sensing (CS) framework is built for ballistocardiography (BCG) signals, which contains two parts of an optical fiber sensor-based heart monitoring system with a CS module and an end-to-end deep learning-based reconstruction algorithm. The heart monitoring system collects BCG data, and then compresses and transmits the data through the CS module at the sensing end. The deep learning-based algorithm reconstructs compressed data at the received end. To evaluate results, three traditional CS reconstruction algorithms and a deep learning method are adopted as references to reconstruct the compressed BCG data with different compression ratios (CRs). Results show that our framework can reconstruct signals successfully when the CR grows from 50% to 95% and outperforms other methods at high CRs. The mean absolute error (MAE) of the estimated heartbeat rate (HR) is lower than 1 bpm when the CR is below 95%. The proposed CS framework for BCG signals can be integrated into the IoMT system, which has great potential in health care for both medical and home use.

关键词： Fiber Bragg grating sensors Fiber interferometry Optical fibers Optical signals Phase modulation reconstruction algorithms

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Underwater single photon 3D imaging with millimeter depth accuracy and reduced blind range

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OPTICS EXPRESS 2023年第19期31卷 30588-30603页

作者： Wang, Jie Hao, Wei Chen, Songmao Zhang, Zhenyang Xu, Weihao Xie, Meilin Zhu, Wenhua Su, Xiuqin Chinese Acad Sci Xian Inst Opt & Precis Mech Key Lab Space Precis Measurement Technol Xian 710119 Peoples R China Chinese Acad Sci Xian Inst Opt & Precis Mech Ctr Shared Technol & Facil Xian 710119 Peoples R China Univ Chinese Acad Sci Beijing 100049 Peoples R China Pilot Natl Lab Marine Sci & Technol Qingdao 266237 Peoples R China Jiujiang Univ Sch Elect & Informat Engn Jiujiang 332005 Peoples R China

Mono-static system benefits from its more flexible field of view and simplified structure, however, the backreflection photons from mono-static system lead to count loss for target detection. Counting loss engender range-blind, impeding the accurate acquisition of target depth. In this paper, count loss is reduced by introducing a polarization-based underwater mono-static single-photon imaging method, and hence reduced blind range. The proposed method exploits the polarization characteristic of light to effectively reduce the count loss of the target, thus improving the target detection efficiency. Experiments demonstrate that the target profile can be visually identified under our method, while the unpolarization system can not. Moreover, the ranging precision of system reaches millimeter-level. Finally, the target profile is reconstructed using non-local pixel correlations algorithm. (c) 2023 Optica Publishing Group under the terms of the Optica Open Access Publishing Agreement

关键词： Image quality Imaging noise Imaging techniques reconstruction algorithms Three dimensional imaging Underwater imaging

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Initial probe function construction in ptychography based on zone-plate optics

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APPLIED OPTICS 2023年第14期62卷 3542-3550页

作者： Qin, Zeping Xu, Zijian Li, Ruoru Liu, Haigang Liu, Shilei Wen, Qingcao Chen, Xing Zhang, Xiangzhi Tai, Renzhong Chinese Acad Sci Shanghai Inst Appl Phys Shanghai 201800 Peoples R China Chinese Acad Sci Shanghai Adv Res Inst Shanghai Synchrotron Radiat Facil Shanghai 201204 Peoples R China Univ Chinese Acad Sci Beijing 100049 Peoples R China Shanghai Tech Univ Sch Phys Sci & Technol Shanghai 201210 Peoples R China

X-ray ptychography is a popular variant of coherent diffraction imaging that offers ultrahigh resolution for extended samples. In x-ray ptychography instruments, the Fresnel zone-plate (FZP) is the most commonly used optical probe system for both soft x-ray and hard x-ray. In FZP-based ptychography with a highly curved defocus probe wavefront, the reconstructed image quality can be significantly impacted by the initial probe function form, necessitating the construction of a suitable initial probe for successful reconstruction. To investigate the effects of initial probe forms on FZP-based ptychography reconstruction, we constructed four single-mode initial probe models (IPMs) and three multi-mode IPMs in this study, and systematically compared their corresponding simulated and experimental reconstructions. The results show that the Fresnel IPM, spherical IPM, and Fresnel-based multi-mode IPMs can result in successful reconstructions for both near-focus and defocus cases, while random IPMs and constant IPMs work only for near-focus cases. Consequently, for FZP-based ptychography, the elaborately constructed IPMs that closely resemble real probes in wavefront phase form are more advantageous than natural IPMs such as the random or constant model. Furthermore, these IPMs with high phase similarity to the high-curvature large-sized probe adopted in experiments can help greatly improve ptychography experiment efficiency and decrease radiation damage to samples. (c) 2023 Optica Publishing Group

关键词： Hard x rays Image quality Phase retrieval reconstruction algorithms Soft x rays X ray imaging

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Phase aberration adaptive compensation in digital holography based on phase imitation and metric optimization

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OPTICS EXPRESS 2023年第13期31卷 21048-21062页

作者： Chen, Zhenkai Zhou, Wenjing Zhang, Hongbo Yu, Yingjie Shanghai Univ Dept Precis Mech Engn Shanghai 200444 Peoples R China China Greece Belt & Rd Joint Lab Cultural Heritage Beijing Peoples R China Middle Tennessee State Univ Dept Engn Technol Murfreesboro TN 37127 USA

We proposed a numerical and accurate quadratic phase aberration compensation method in digital holography. A phase imitation method based on Gaussian 1 & sigma;-criterion is used to obtain the morphological features of the object phase using partial differential, filtering and integration successively. We also propose an adaptive compensation method based on a maximum-minimum -average-& alpha;-standard deviation (MMA & alpha;SD) evaluation metric to obtain optimal compensated coefficients by minimizing the above metric of the compensation function. The effectiveness and robustness of our method are demonstrated by simulation and experiments. & COPY;2023 Optica Publishing Group under the terms of the Optica Open Access Publishing Agreement

关键词： Aberration compensation Digital holographic imaging Phase compensation Phase contrast imaging Phase shift reconstruction algorithms

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Distributed optical synthetic aperture position-transformed method with high-frequency domain coverage

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OPTICS EXPRESS 2023年第20期31卷 32298-32310页

作者： Zhang, Kui Bao, Weimin Fang, Haiyan Li, Xiaoping Song, Yufeng Xidian Univ Sch Aerosp Sci & Technol Xian 710126 Peoples R China

Realizing an ultrahigh-equivalent aperture for space-based direct optical detection using a distributed optical synthetic aperture (DOSA) system with a very low filling ratio is challenging. This study proposes a position-transformation method for DOSA systems with high-frequency domain coverage called High-Frequency domain-Covering discrete Archimedean Spiral Arrays (HFCASA). The study shows that Golay3 HFCASA with a filling ratio of 0.0675% can greatly improve frequency domain coverage and fulfill the resolution requirements of a 200 m aperture telescope. HFCASA provides the theoretical basis for the future deep-space exploration of DOSA.(c) 2023 Optica Publishing Group under the terms of the Optica Open Access Publishing Agreement

关键词： Aperture synthesis Image processing algorithms Image reconstruction Optical detection reconstruction algorithms Synthetic aperture imaging

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Image Compressed Sensing Using Non-Local Neural Network

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IEEE TRANSACTIONS ON MULTIMEDIA 2023年 25卷 816-830页

作者： Cui, Wenxue Liu, Shaohui Jiang, Feng Zhao, Debin Harbin Inst Technol Dept Comp Sci & Technol Harbin 150001 Peoples R China Peng Cheng Lab Shenzhen 518055 Peoples R China

Deep network-based image Compressed Sensing (CS) has attracted much attention in recent years. However, the existing deep network-based CS schemes either reconstruct the target image in a block-by-block manner that leads to serious block artifacts or train the deep network as a black box that brings about limited insights of image prior knowledge. In this paper, a novel image CS framework using non-local neural network (NL-CSNet) is proposed, which utilizes the non-local self-similarity priors with deep network to improve the reconstruction quality. In the proposed NL-CSNet, two non-local subnetworks are constructed for utilizing the non-local self-similarity priors in the measurement domain and the multi-scale feature domain respectively. Specifically, in the subnetwork of measurement domain, the long-distance dependencies between the measurements of different image blocks are established for better initial reconstruction. Analogically, in the subnetwork of multi-scale feature domain, the affinities between the dense feature representations are explored in the multi-scale space for deep reconstruction. Furthermore, a novel loss function is developed to enhance the coupling between the non-local representations, which also enables an end-to-end training of NL-CSNet. Extensive experiments manifest that NL-CSNet outperforms existing state-of-the-art CS methods, while maintaining fast computational speed.

关键词： Image reconstruction Neural networks reconstruction algorithms Training Noise reduction Iterative algorithms Current measurement Convolutional neural networks (CNNs) image compressed sensing non-local neural network non-local self-similarity prior

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Phase-Only Compact Radiation-Type Metasurfaces for Customized Far-Field Manipulation

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IEEE TRANSACTIONS ON MICROWAVE THEORY AND TECHNIQUES 2023年第9期71卷 4119-4128页

作者： Wang, Yuzhong Pang, Cheng Wang, Qiming Mu, Yongheng Cheng, Yayun Qi, Jiaran Harbin Inst Technol Sch Elect & Informat Engn Harbin 150001 Peoples R China

Microwave metasurfaces are often difficult to apply in integrated systems due to the required spatial feeds. Herein, a compact circularly polarized (CP) radiation-type metasurface (RTM) realizing precise far-field radiation pattern manipulation is proposed. Two e-shaped elements are superimposed to con-stitute the meta-atoms based on the geometric phase, exhibiting a full 2p transmission phase coverage and high transmittance. Moreover, a far-field reconstruction method based on phase mask optimization is proposed to realize highly customized far-field pattern control. Several proof-of-concept RTM prototypes, real-izing energy-tailorable multibeams, wide angle deflection, and customized beam shaping, are designed and fabricated. The simulation and the experimental results validate the proposed method and the RTM structures, which may offer compact wave modulation components capable of highly precise and customized far-field beamforming.

关键词： Metasurfaces Phase modulation Modulation reconstruction algorithms Microstrip Impedance Surface impedance Energy-controllable beams fan beams far-field manipulation multibeam radiation-type

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Spatially encoded hyperspectral compressive microscope for ultrabroadband VIS/NIR hyperspectral imaging

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APPLIED OPTICS 2023年第15期62卷 4030-4039页

作者： Klein, Lukas Tous, Jan Zidek, Karel Czech Acad Sci Reg Ctr Special Opt & Optoelect Syst TOPTEC Inst Plasma Phys Slovankou 1782-3 Prague 8 Czech Republic Tech Univ Liberec Fac Mechatron Informat & Interdisciplinary Studies Studentska 1402-2 Liberec 46117 Czech Republic Spol Sro Crytur Lukach 2283 Turnov 51101 Czech Republic

Hyperspectral imaging (HSI) has become a valuable tool in sample characterization in various scientific fields. While many approaches have been tested, specific applications and technology usually lead to only a narrow part of the spectrum being studied. We demonstrate the use of a broadband HSI setup based on compressed sensing capable of capturing data in visible (VIS), near-infrared (NIR), and short-wave infrared (SWIR) spectral regions. Using a tested design, we developed a dual configuration and tested its performance on a set of samples demon-strating spatial resolution and spectral reconstruction. Samples showing a potential use of the setup in optical defect detection are also tested. The setup showcases a dual single-pixel camera configuration capable of combining various detectors with a shared spatial modulation, further improving data efficiency and providing an affordable instrument from broadband spectral studies. (c) 2023 Optica Publishing Group

关键词： Digital micromirror devices Hyperspectral imaging reconstruction algorithms Spatial resolution Spectroscopy Visible light

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