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Research on an automatic light field refocusing method for a camera array

Optics Express 2025年第10期33卷 20964-20980页

作者： Yihua Pan Yushan Zhao Yuyang Li Bin Liu Ping Chen Shanxi Key Laboratory of Intelligent Detection Technology & Equipment School of Information and Communication Engineering North University of China Taiyuan Shanxi 030051 China Key Laboratory of Photoelectronic Imaging Technology and System of Ministry of Education of China School of Optics and Photonics Beijing Institute of Technology Beijing 100081 China State Key Laboratory of Extreme Environment Optoelectronic Dynamic Testing Technology and Instruments North University of China Taiyuan Shanxi 030051 China

Light field information includes the position and angle information of light in space. A camera array is one of the methods for obtaining light field information, which combines and arranges multiple cameras in space to achieve multi-angle imaging of the same target. Based on the light field information, a computational imaging method can be used to achieve refocusing technology for a camera array (also known as optical synthetic aperture imaging technology). In this technology, by setting the focusing coefficient, the light field information can be focused on different depths. This mode is called taking photos first and focusing later. However, in order to focus on a specific object surface, traditional refocusing methods require users to manually adjust the focusing coefficient multiple times, which is time-consuming and user-unfriendly. Therefore, in this paper, we propose an automatic focusing method based on the optimal focusing coefficient map (OFCM) to address the manual refocusing problem. This method transforms the refocusing problem into obtaining the optimal focus coefficient map. In the process of solving OFCM, the threshold filtering method and the neighborhood filling method are used to optimize the results and improve the robustness of the proposed method. The experimental results show that our proposed method has higher imaging quality and faster running efficiency compared to automatic refocusing methods based on disparity maps and gradient functions.

关键词： Biomedical imaging Computational imaging imaging techniques Plenoptic imaging Point spread function Real time imaging

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An alternative application of GaAs-based light-emitting diodes: X-ray detection and imaging

arXiv

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arXiv 2025年

作者： Yu, Quan Wang, Fangbao Yuan, Xin Liu, Ying Gan, Lianghua Xu, Gangyi Shen, Wenzhong Chen, Liang Zhang, Yueheng Key Laboratory of Artificial Structures and Quantum Control School of Physics and Astronomy Shanghai Jiao Tong University Shanghai200240 China Radiation Detection Research Center Northwest Institute of Nuclear Technology Xi’an710024 China Key Laboratory of Infrared Imaging Materials and Detectors Shanghai Institute of Technical Physics Chinese Academy of Sciences Shanghai200083 China Hangzhou Institute for Advanced Study University of Chinese Academy of Sciences Hangzhou310024 China

GaAs-based light-emitting diodes (LEDs) are commonly employed in a variety of applications, including medical imaging, biosensing, optical communications, and night vision. In this paper, we present an alternative application of GaAs-based LED with SI-GaAs substrate for X-ray detection and imaging. The mechanism relies on the semiconductor frequency down-conversion process, where the SI-GaAs substrate acts as a photodetector (PD). Upon X-ray irradiation, the generated photocurrent by the SI-GaAs substrate drives the LED to emit NIR photons which can be detect by a low-cost CCD. We demonstrate direct X-ray detection and present preliminary imaging results, providing another example of the applicability of the PD-LED design for optical frequency conversion. The proposed LED X-ray detector leverages mature materials and fabrication processes. The application of the frequency down-conversion concept makes it possible for pixel-less imaging using a large single imaging unit, eliminating the need for readout circuits. This PD-LED architecture offers an alternative approach to direct X-ray detection and imaging, characterized by higher absorption, improved image resolution, and enhanced material stability. Copyright © 2025, The Authors. All rights reserved.

关键词： III-V semiconductors

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Structural Damage detection and Localization Using Response Difference Transmissibility

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Journal of Shanghai Jiaotong university(Science) 2024年第6期29卷 1126-1138页

作者： WANG Zengwei DING Lei Shanghai Institute of Technical Physics Key Laboratory of Infrared System Detection and Imaging TechnologyChinese Academy of SciencesShanghai 200083China

In this paper,a novel method is proposed for structural damage detection and *** key of the proposed method is the use of the response difference transmissibility(RDT)for damage *** RDT is defined to relate response differences of the system to be evaluated and those of the original *** invariance properties of RDT are also *** on this,a damage indicator is proposed,and the benefits are verified by a numerical ***,the proposed method is illustrated and validated by finite element simulations and experimental case studies.

关键词： damage detection damage localization transmissibility mechanical vibrations

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A novel method of spike detection for interferograms based on two-step filtering

A novel method of spike detection for interferograms based o...

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4th International Conference on Frontiers of Manufacturing Science and Measuring technology, ICFMM 2014

作者： Zou, Yao Pu Han, Chang Pei Zhang, Lei Pan, Wen Gui Wang, Chao Key Laboratory of Infrared System Detection and Imaging Technology SITP UCAS China

ISBN: (纸本)9783038351924

According to the characteristics of interferogram, we design a new spike detection method, which firstly filters an interferogram with two different ways and then detects spikes based on both results. Theoretical analysis and computer simulation shows that this algorithm performs well in detecting spikes in any position of an interferogram with high accuracy, and can be easily implemented in hardware. © (2014) Trans Tech Publications, Switzerland.

关键词： Computer hardware

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A method to compensate the dead time for three-phase PWM inverters

A method to compensate the dead time for three-phase PWM inv...

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International Conference on Frontiers of Energy, Materials and Information Engineering, ICFMEI 2014

作者： Pan, Wen Gui Zhang, Lei Zou, Yao Pu Wang, Chao Han, Chang Pei Key Laboratory of Infrared System Detection and Imaging Technology SITP UCAS Shanghai China

ISBN: (纸本)9783038352778

As for a vector control of a permanent magnet synchronous motor, this paper analyzed the influence of dead-time effect of three-phase bridge inverters on output voltage and current in details. A novel on-line method was proposed for dead-time effect compensation based on disturbance observer. At last, the method is simulated using MATLAB and the simulation results proves the effectiveness and feasibility of the method presented. © (2014) Trans Tech Publications, Switzerland.

关键词： Pulse width modulation

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A design of on-board dual-channel data handling method based on two FPGAs 6

A design of on-board dual-channel data handling method based...

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6th International SpaceWire Conference, SpaceWire 2014

作者： Yaopu, Zou Jiayou, Jiang Changpei, Han Key Laboratory of Infrared System Detection and Imaging Technology Shanghai Institute of Technical Physics UCAS Shanghai China Key Laboratory of Infrared System Detection and Imaging Technology Shanghai Institute of Technical Physics CAS Shanghai China

ISBN: (纸本)9780955719653

SpaceWire is used on FY4 meteorological satellite as on-board data-handling network. Based on SpaceWire, this paper provides a design using two FPGAs and AT7911 chips for the dual-channel data processing of a payload on FY4 to ensure that data can be transported efficiently and reliably. This design has proved to be feasible when tested on the ground. © 2014 University of Dundee.

关键词： Data handling

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High-accuracy source-independent radiometric calibration with low complexity for infrared photonic sensors

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Light(Science & Applications) 2021年第9期10卷 1714-1725页

作者： Qiang Guo Fuchun Chen Xiangyang Li Boyang Chen Xin Wang Guilin Chen Caiying Wei National Satellite Meteorological Center China Meteorological Administration100081BeijingChina Key Laboratory of Infrared System Detection&Imaging Technology Shanghai Institute of Technical PhysicsChinese Academy of Sciences200083ShanghaiChina Key Laboratory of Infrared Imaging Materials&Detectors Shanghai Institute of Technical PhysicsChinese Academy of Sciences200083ShanghaiChina

Radiometric calibration(RC)is an essential solution to guarantee measurements from infrared photonic sensors with certain accuracy,the main task of which is to determine the radiometric responsivity of sensor and usually be solved by comparing with some radiation source(i.e.,blackbody),called source-based RC(SBRC).In addition to the complexity in manufacture,the nonideal characteristics of an available source will inevitably introduce unexpected uncertainties to reduce the final calibration accuracy by around 0.2–0.5 K in ***,we propose an original source-independent RC(SIRC)principle based on modeling instead of comparing for SBRC,where the incident background radiation to detector,as a dominated factor influencing the responsivity characteristics of a photonic sensor,is modeled to implement RC for both two fundamental types(photoconductive and photovoltaic)of HgCdTe photonic *** SIRC merely requires the temperature information of main components of a sensor other than some complex source and its assembly,and provides a traceable way at lower uncertainty costs relative to the traditional *** SIRC is being implemented in Fengyun-2 satellites since 2019,which ensures a long-term stable service of Chinese geostationary meteorological satellites for the global observation system under the framework of World Meteorological ***,a 20-year-period traceable Fengyun-2 dataset to be recalibrated with SIRC will benefit the further climate applications.

关键词： source complexity calibration

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CO2 monitoring spectrometer with 640x512 Pixel SWIR InGaAs focal plane array

CO2 monitoring spectrometer with 640x512 Pixel SWIR InGaAs f...

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2012 International Symposium on Photonics and Optoelectronics, SOPO 2012

作者： Peng, Wei Wu, Shixiang Ding, Lei Wang, Xianghua Hou, Yihe Liu, Jiaqing Tan, Chan Liu, Yuxuan Key Laboratory of Infrared System Detection and Imaging Technology Shanghai Institute of Technical Physics Chinese Academy of Sciences Shanghai China

ISBN: (纸本)9781457709111

This paper introduces a prototype grating spectrometer measuring atmospheric column carbon dioxide (CO2) with a 640x512 pixel indium gallium arsenide (InGaAs) focal plane array (FPA). The spectrometer achieves the spectral resolutions of 0.1 nm at 1.61μm CO2 band meets the measurement requirement. The structure of the spectrometer including optics and electronics has been described in this paper. The spectrometer features a relatively fast optics, f/1.8, which benefits the sensitivity, and combines a fine slit with a large planar reflective diffraction grating. The performance of the optical design is presented to demonstrate the optical system meets the requirements for spectral resolution and sensitivity. The 640x512 InGaAs FPA with a low noise acquisition system serves to provide low noise spectral signals. The 640x512 InGaAs FPA, 25 μm pixel size, is sensitive to 0.9μm-to-1.7μm short wave infrared (SWIR) band and features a 298 K temperature detectivity, D*, greater than 5×1012 cm -1√Hz/W. © 2012 IEEE.

关键词： Carbon dioxide

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Design and simulation of image compensation control system

Design and simulation of image compensation control system

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2013 International Conference on Mechatronics and Automatic Control systems, ICMS 2013

作者： Tan, Chan Ding, Lei Key Laboratory of Infrared System Detection and Imaging Technology Shanghai Institute of Technical Physics Chinese Academy of Sciences Shanghai China

ISBN: (纸本)9783319012728

Image compensation is a key to high resolution imaging. This paper designs and simulates an image compensation control system based on swing pointing mirror. The principle of pointing mirror compensation is presented and the mathematical model of pointing mirror's driving motor is established. Based on this model, a high accurate controller which consists of current loop and velocity loop is designed and simulated. Considering that there is disadvantage of traditional speed PID controller in dynamic performance, which is speed overshoot, the speed loop adopts pseudo derivative feed-forward (PDFF) controller. Theoretical analysis and simulation results show that the designed image compensation control system has good characteristic in following performance, dynamic response and noise resistance. © Springer International Publishing Switzerland 2014.

关键词： Controllers

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Numerical Validation of A Simple Dynamic Beam Filtration Strategy in Cone Beam CT

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集成技术 2025年第2期14卷 71-85页

作者： WANG Heran XIE Jixiong ZHU Jiongtao ZHANG Xin TAN Yuhang SU Ting GE Yongshuai Shenzhen Institutes of Advanced Technology Chinese Academy of SciencesShenzhen 518055China University of Chinese Academy of Sciences Beijing 100049China Research Center for Advanced Detection Materials and Medical Imaging Devices Shenzhen Institutes of Advanced TechnologyChinese Academy of SciencesShenzhen 518055China Paul C.Lauterbur Research Center for Biomedical Imaging Shenzhen Institutes of Advanced TechnologyChinese Academy of SciencesShenzhen 518055China Key Laboratory of Biomedical Imaging Science and System Chinese Academy of SciencesShenzhen 518055China

For cone beam computed tomography(CBCT),there has long been a desire to modulate the intensity and distribution of the X-rays to accommodate the patient’s anatomy as the gantry rotates from one projection to *** would reduce both image artifacts and radiation ***,the current beam modulation setups,such as dynamic bowtie filters,may be too complex for practical use in clinical *** study aimed to investigate a simplified dynamic beam filtration strategy for CBCT imaging to reduce image artifacts and radiation *** this study,the beam filtration was designed to vary dynamically as the CBCT gantry rotates around the ***,two distinct components were integrated:the sheet filter part and the bowtie filter *** dynamic beam filtration setup has two working schemes,one is a combination of dynamic sheet filter and dynamic bowtie filter,denoted as dynamic filterdynamic bowtie(DFDB);the other is a combination of dynamic sheet filter and static bowtie filter,denoted as dynamic filter-static bowtie(DFSB).Numerical imaging experiments were performed for three human body parts:the shoulder,chest,and *** addition,the Monte Carlo simulation platform MC-GPU was used to generate the dose distribution *** showed that the proposed DFDB and DFSB beam filtration schemes can significantly reduce the image artifacts and thus improve the CBCT image *** on the scanned object,the total radiation dose could be reduced by 30%.The proposed simple dynamic beam filtration strategy,especially the DFSB approach,could be beneficial in the future to improve the CBCT image quality with reduced image artifacts and radiation dose.

关键词： dynamic filtration radiation dose reduction artifacts reduction cone beam computed tomography

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