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Record 529 of
Title:Two-stage frequency compensation for Doppler shift on BPSK transceiver with LDPC codes for free-space optical communication systems
Author(s):Meng, Jiacheng(1,2); Wei, Tingting(1); Wang, Yufei(1); Bai, Zhaofeng(1,2); Wu, Junxia(1); Gao, Duorui(1,2); Xie, Zhuang(2); Zheng, Yunqiang(1); Nie, Wenchao(1); Wei, Sentao(1); Wang, Wei(1,2); Xie, Xiaoping(1,2)
Source: Frontiers in Physics Volume: 11 Issue: null Article Number: 1099867 DOI: 10.3389/fphy.2023.1099867 Published: 2023
Abstract:The deployment of low earth orbits is seen as a promising way of enlarging data capacities as well as high data rates. Catering to these interests, optical communication presents possible ways of larger bandwidth than microwave communication. The current generation of mainstream communication systems are classified as coherent systems and incoherent systems, and in particular, coherent systems have received more attention owing to their high receiving sensitivity. This study investigates a digital coherent transceiver, based on binary phase-shift keying technology. As coherent demodulation will be affected by considering the Doppler shift effect in digital demodulation, Doppler shift of ± GHz can be compensated by adopting a two-stage frequency offset compensation. Moreover, by leveraging a fast filtering algorithm a considerable amount of resource consumption is saved in its engineering implementation, and its sensitivity can be significantly enhanced via a high-speed parallel error-correction codec based on low-density parity-check technology. Copyright ? 2023 Meng, Wei, Wang, Bai, Wu, Gao, Xie, Zheng, Nie, Wei, Wang and Xie.
Accession Number: 20233514651741
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Record 530 of
Title:High Precision Polarization Image Reconstruction Algorithm Based on Depth Residual Convolutional Neural Network- In Situ Replacement Optimization
Author(s):Bu, Fan(1); Yao, Dalei(1); Cao, Weicheng(1); Yang, Yongqing(1); Wang, Xueli(2)
Source: Proceedings of SPIE - The International Society for Optical Engineering Volume: 12921 Issue: null Article Number: 129212G DOI: 10.1117/12.2690430 Published: 2023
Abstract:Compared to traditional polarization imaging methods such as time sharing, amplitude sharing, and aperture sharing, the division of focal-plane polarimeter (DOFP) polarization imaging method has obvious advantages such as simultaneous imaging, compact optical and mechanical structure, small size, low power consumption, and high reliability. Therefore, this technology is currently a research hotspot in the field of polarization imaging. However, the focal plane polarization imaging technology uses a micro polarization array (MPA) detector, which only captures a single polarization direction for a pixel, resulting in reduced spatial resolution of polarization images. In order to improve spatial resolution and the impact of factors such as unit mismatch in traditional interpolation methods on the detection system, this paper proposes a polarization image interpolation method based on depth residual convolution neural network. This algorithm closely combines the periodic phase characteristics of focal plane polarized images, designs a matched phase convolution kernel for feature extraction based on the pattern periodicity of four channel polarized image blocks, and designs a demosaic image interpolation method based on generating confrontation networks and phase convolution. Experimental results show that this algorithm can effectively reconstruct full resolution polarized images, and is superior to traditional methods in terms of vision and Grayscale Mean Gradient(G) . ? 2023 SPIE.
Accession Number: 20234815132646
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Record 531 of
Title:Optical mechanical thermal integration analysis of gravitational wave detection telescope system
Author(s):Yao, Kaizhong(1,2); Li, Xuyang(1,2); Yuan, Hao(1,2)
Source: Proceedings of SPIE - The International Society for Optical Engineering Volume: 12964 Issue: null Article Number: 129640C DOI: 10.1117/12.3006412 Published: 2023
Abstract:The gravitational wave detection telescope system is located in a space environment and will be subject to radiation from the sun and Earth, as well as internal thermal power consumption. These factors will cause the gravitational wave detection telescope to be in a changing temperature environment. Due to the effects of structures such as light shields and insulation layers, the temperature environment of the optical system can be equivalent to a steady-state thermal equilibrium environment. Using an optical design software and finite element simulation software combined with an optical mechanical thermal integration design method, simulate the vacuum thermal equilibrium experimental states of the optical system at ambient temperatures of -15 ℃, -5 ℃, 5 ℃, 15 ℃, 22 ℃, 35 ℃, and 45 ℃, and analyze the root mean square values of wavefront error, peak valley values of wavefront error, and reference light offset values for different states. At the same time, the vibration experiment of the optical system is simulated, linking mechanical vibration with optical performance analysis indicators, analyzing the PSD response function of mirror deformation RMS value under different working conditions, and the modes that have a significant impact on the composition image of the optical imaging lens. ? 2023 SPIE.
Accession Number: 20240315394891
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Record 532 of
Title:Imaging-based methods for lunar dust flux and velocity measurement
Author(s):Dai, Yidan(1,2); Xue, Bin(1); Tao, Jinyou(1,2); Yang, Jianfeng(1)
Source: Proceedings of SPIE - The International Society for Optical Engineering Volume: 12921 Issue: null Article Number: 129210B DOI: 10.1117/12.2687484 Published: 2023
Abstract:Lunar dust is widely distributed on the lunar surface as tiny particles ranging from 30nm to 20μm. Currently, extensive research has been conducted on the physical, chemical, and hazardous properties of lunar dust. However, few studies focused on its motion patterns and related mechanisms. This paper aims to utilize non-contact imaging method for the first time to record and analyze the trajectory and velocity of lunar dust movement. The fundamental principle of this paper is to use a high-sensitivity camera to image the dust particles in the detection area within a certain exposure time, and to obtain the intensity of the scattered light from the particles in the detection area at that exposure time based on the grayscale value. In terms of velocity measurement, the spatial motion trajectory of lunar dust was recorded by the single frame multi-exposure imaging method, and the related algorithm based on gray value distribution of the motion trajectory image was used to calculate its velocity. In considering the small particle size of lunar dust would cause weak light scattering energy, during the construction of the principle prototype, the strong pulse laser technology was used to increase the illumination, and the sCMOS camera with a far-field optical lens was adopted to improve the signal detection sensitivity. The results showed that the prototype can identify particles from 0.3μm to 20μm, measure velocity from 1m/s to 100m/s, and the minimum detectable dust concentration is 1000pc/ft3. This study provides technical reserves for lunar dust environment exploration in future lunar exploration projects. ? 2023 SPIE.
Accession Number: 20234815132537
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Record 533 of
Title:Sanxingdui Cultural Relics Recognition Algorithm Based on Hyperspectral Multi-Network Fusion
Author(s):Qiu, Shi(1); Zhang, Pengchang(1); Tang, Xingjia(2); Zeng, Zimu(1); Zhang, Miao(1); Hu, Bingliang(1)
Source: Computers, Materials and Continua Volume: 77 Issue: 3 Article Number: null DOI: 10.32604/cmc.2023.042074 Published: 2023
Abstract:Sanxingdui cultural relics are the precious cultural heritage of humanity with high values of history, science, culture, art and research. However, mainstream analytical methods are contacting and detrimental, which is unfavorable to the protection of cultural relics. This paper improves the accuracy of the extraction, location, and analysis of artifacts using hyperspectral methods. To improve the accuracy of cultural relic mining, positioning, and analysis, the segmentation algorithm of Sanxingdui cultural relics based on the spatial spectrum integrated network is proposed with the support of hyperspectral techniques. Firstly, region stitching algorithm based on the relative position of hyper spectrally collected data is proposed to improve stitching efficiency. Secondly, given the prominence of traditional HRNet (High-Resolution Net) models in high-resolution data processing, the spatial attention mechanism is put forward to obtain spatial dimension information. Thirdly, in view of the prominence of 3D networks in spectral information acquisition, the pyramid 3D residual network model is proposed to obtain internal spectral dimensional information. Fourthly, four kinds of fusion methods at the level of data and decision are presented to achieve cultural relic labeling. As shown by the experiment results, the proposed network adopts an integrated method of data-level and decision-level, which achieves the optimal average accuracy of identification 0.84, realizes shallow coverage of cultural relics labeling, and effectively supports the mining and protection of cultural relics. ? 2023 Tech Science Press. All rights reserved.
Accession Number: 20240115314677
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Record 534 of
Title:Simulation research on CCD noise reduction algorithm based on digital correlation double sampling
Author(s):Yao, Dalei(1,2); Luo, Jianjun(1); Bu, Fan(2); Wen, Yan(2); Yang, Yongqing(2); Cao, Weicheng(2); Ye, Shuifu(2)
Source: Proceedings of SPIE - The International Society for Optical Engineering Volume: 12747 Issue: null Article Number: 127471X DOI: 10.1117/12.2689203 Published: 2023
Abstract:As a new low noise CCD signal processing technology, digital correlation double sampling noise reduction technology is widely used in the field of faint astronomical target detection. In this paper, various noise sources of CCD video processing circuit are studied, the characteristics of various noises are analyzed deeply, the mathematical model of CCD circuit noise is established, and a noise reduction method based on digital correlation double sampling technology is proposed. Through simulation modeling of CCD noise signal, the simulation results show that the digital correlation double sampling method using double Gaussian filter function has a good effect on noise suppression. ? 2023 SPIE. All rights reserved.
Accession Number: 20235115263091
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Record 535 of
Title:Research on SAR image target classification based on attention mechanism and data enhancement
Author(s):Ji, Ran(1,2); Xiao, Maosen(1); Li, Shuo(1,2)
Source: Proceedings of SPIE - The International Society for Optical Engineering Volume: 12918 Issue: null Article Number: 1291824 DOI: 10.1117/12.3009306 Published: 2023
Abstract:Classifying the equipment type of hostile targets in military applications in SAR images is crucial and requires higher classification accuracy. Using data enhancement techniques, this paper conducts an experimental study on the classification of MSTAR dataset using a convolutional neural network with the addition of an attention mechanism and obtains the advantages of strong generalization ability, fast training speed, and high fitting efficiency of the target classification method proposed in this paper. ? 2023 SPIE.
Accession Number: 20234615045826
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Record 536 of
Title:Research on Smear Effect Modeling of Frame Transfer CCD Sensor
Author(s):Yao, Dalei(1,2); Luo, Jianjun(1); Bu, Fan(2); Wen, Yan(2); Yongqing, Yang(2); Cao, Weichen(2)
Source: Proceedings of SPIE - The International Society for Optical Engineering Volume: 12921 Issue: null Article Number: 129211F DOI: 10.1117/12.2688296 Published: 2023
Abstract:During astronomical observations, the CCD sensor will produce the Smear effect during frame transfer, and the Smear effect will pollute the column pixels corresponding to the image, thus affecting target detection. According to the characteristics of frame transfer CCD, the generation of Smear effect is analyzed, and the gray scale analysis model of the Smear effect is established, which simulates the gray value corresponding to the Smear effect generated by astronomical observation cameras when detecting targets of different magnitudes, and verifies it through experiments. The theoretical analysis in this paper provides an important reference for the design of astronomical cameras. ? 2023 SPIE.
Accession Number: 20234815132567
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Record 537 of
Title:Design of compact off-axis three-mirror freeform optical system with small F number
Author(s):Ning, Mo(1,2); Mao, Xianglong(1); Yu, Jiadong(1); Yuan, Ying(1); Yang, Jiating(1); Cai, Zhaohan(1,2); Xie, Yongjun(1)
Source: Proceedings of SPIE - The International Society for Optical Engineering Volume: 12964 Issue: null Article Number: 129640E DOI: 10.1117/12.3007600 Published: 2023
Abstract:In the field of space optics, the compact freeform optical imaging system with small F number can realize the miniaturization and lightweight of the load, which is beneficial to enhance the ability of target recognition. In this paper, according to the vector aberration theory and the principle of Gaussian brackets, the error evaluation function is constructed by the primary wave aberration coefficients and focal length constraint of the system1, and the dynamic weight is used to limit difference in the order of magnitude between various aberrations, which is conducive to rapid convergence in the process of solving the initial structural parameters. In order to achieve the compactness of the system, the circular layout is adopted. The unobstructed initial structure of the off-axis reflective system with conic surfaces is obtained through Particle Swarm Optimization (PSO) algorithm, and the off-axis three-mirror freeform optical system with a highly compact layout is obtained after optimization. In addition, considering the difficulty of freeform surfaces manufacturing, add the manufacturability constraint to the optimization process to control the degree of departure between the aperture edge of the freeform surfaces and the conic surfaces in real time. Compared with the optical system obtained without manufacturability constraints, the difficulty of manufacturing is effectively reduced. ? 2023 SPIE.
Accession Number: 20240315394893
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Record 538 of
Title:Asymmetric localized states at a nonlinear interface of fractional systems with optical lattices
Author(s):Zhou, Shu(1,2); Zeng, Jianhua(2,3); Qin, Yali(1)
Source: Frontiers in Physics Volume: 10 Issue: null Article Number: 1116344 DOI: 10.3389/fphy.2022.1116344 Published: January 26, 2023
Abstract:We investigate the existence and stability of localized gap states at a non-linear interface of non-linear fractional systems in a one-dimensional photonic lattice. By using the direct numerical simulations and linear stability analysis, we obtain the stability of the asymmetric localized gap states in the first and second finite gaps. Our theoretical results show that the power of the localized gap states decrease gradually as the increase of propagation constant and the non-linear landscape (non-linear coefficient ratio between the left and right interface), providing insights into soliton physics in non-linear periodic systems with fractional-order diffraction. Copyright ? 2023 Zhou, Zeng and Qin.
Accession Number: 20233514654220
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Record 539 of
Title:Editorial: Optical microscopy: advances and applications
Author(s):Dan, Dan(1)
Source: Frontiers in Physics Volume: 11 Issue: null Article Number: 1337300 DOI: 10.3389/fphy.2023.1337300 Published: 2023
Abstract:null
Accession Number: 20235015207637
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Record 540 of
Title:Analysis of output torque stability of single gimbal control moment gyroscope
Author(s):Wang, Yiming(1); Liu, Jun(1); Xie, Meilin(1); Wang, Fan(1); Cheng, Zhiyuan(1)
Source: Proceedings of SPIE - The International Society for Optical Engineering Volume: 12940 Issue: null Article Number: 129401H DOI: 10.1117/12.3010626 Published: 2023
Abstract:The control accuracy of Single Gimbal Control Moment Gyroscope (SGCMG) is limited by the existence of interference factors such as dynamic imbalances. This paper analyzes the output torque disturbance of SGCMG from a dynamic perspective and verifies the influence weights of disturbance factors through simulations, providing a reference for the control of torque output stability in SGCMG. Firstly, considering factors such as static and dynamic imbalance, installation errors of the high-speed rotor system using the Newton-Euler method, a preliminary analysis of each subsystem is conducted. Secondly, considering disturbance factors such as frame speed, a dynamic model analysis is performed. Finally, based on actual parameter values, the characteristics of the system's output torque are analyzed through simulations. Experimental results show that the torque output process of the system is stable under ideal conditions. However, in the presence of disturbances such as dynamic imbalance, the stability of SGCMG's torque output process is influenced to varying degrees. The analysis of the influence weights of various disturbance factors is accomplished using principal component analysis. ? 2023 SPIE.
Accession Number: 20235015225414
