2022
2022
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Record 121 of
Title:Structure design of the shutter with slider-crank mechanism
Author(s):Jiaqi, F.E.I.(1)Source: ACM International Conference Proceeding Series Volume: Issue: DOI: 10.1145/3517077.3517119 Published: January 14, 2022Abstract:In order to realize the miniaturization and lightweight of the infrared nonuniform correction shutter, the crank slider mechanism is used to design. Firstly, the shutter blade is used as the slider and the driving mechanism is used as the crank, and the motion analysis is carried out. The transmission angle of the crank slider mechanism is calculated to be no less than 66.42 °. Then, the slider, connecting rod and crank are analyzed respectively, the force system and motion equation are established, and the driving torque of the shutter is calculated. The design results show that the volume, weight and driving torque of the same target product are reduced by 1 / 3, 1 / 2 and 1 / 2, respectively, compared with the direct motion rotary shutter commonly used in nonuniform correction of infrared camera. The design goal is achieved. ? 2022 Owner/Author.Accession Number: 20222312201903 -
Record 122 of
Title:Camera Design and Performance for the Earth 2.0 Mission
Author(s):Song, Zongxi(1); Li, Wei(1); Wang, Fengtao(1); Cheng, Pengfei(1); Shen, Chao(1); Pan, Yue(1); Gao, Wei(1); Li, Yan(2); Zhang, Hui(2); Ge, Jian(2)Source: Proceedings of SPIE - The International Society for Optical Engineering Volume: 12180 Issue: DOI: 10.1117/12.2630652 Published: 2022Abstract:The Earth 2.0 (ET) mission is a Chinese space mission to detect thousands of Earth-sized terrestrial planets, including habitable Earth-like planets orbiting solar type stars (Earth 2.0s), cold low-mass planets, and free-floating planets. The six 30 cm diameter transit telescopes will be equipped with a CMOS camera which consists of 4（2×2）9K×9K CMOS sensors. A prototype camera with a 8900×9120 pixel GSENSE 1081 BSI type CMOS sensor and temperature control is designed and developed for high precision photometry measurements. In this paper, details of this camera design and performance test results are reported. ? 2022 SPIE.Accession Number: 20230413449647 -
Record 123 of
Title:Collaborative representation with multipurification processing and local salient weight for hyperspectral anomaly detection
Author(s):Wang, Nan(1,2); Shi, Yuetian(1,2); Yang, Fanchao(1); Zhang, Geng(1); Li, Siyuan(1); Liu, Xuebin(1)Source: Journal of Applied Remote Sensing Volume: 16 Issue: 3 DOI: 10.1117/1.JRS.16.036517 Published: July 1, 2022Abstract:Anomalous objects detection for hyperspectral imagery is a significant branch in the area of remote sensing. Although enormous advancements have been developed, issues of redundancy of spectral information and correlation between pixels should be further explored and improved. To address these problems, we proposed a method that is on the basis of integrating collaborative representation with multipurification processing and local salient weight. Multipurification processing consists of spectral bands purification (SBP) and background purification (BGP). First, to alleviate the interference of redundant spectral information, we remove unnecessary spectral bands by adopting SBP based on considering the global spectral intensity of each band. Then, we remove the outliers in the local dual window by BGP to avoid the effect of heterogeneous pixels. Simultaneously, we obtain the local salient weight by calculating the similarity and difference of pixels in the dual window. Next, we obtain the initial detection result by a collaborative representation, which has been testified to be very effective. Finally, combined with the local salient weight map, the initial detection map is improved to the final detection map. To demonstrate the superiority of the proposed method, we conducted the comprehensive experiment on three public benchmark datasets that contain 15 hyperspectral images. ? 2022 Society of Photo-Optical Instrumentation Engineers (SPIE).Accession Number: 20234715089536 -
Record 124 of
Title:Cross-Attention Spectral-Spatial Network for Hyperspectral Image Classification
Author(s):Yang, Kai(1,2); Sun, Hao(1,2); Zou, Chunbo(1); Lu, Xiaoqiang(1)Source: IEEE Transactions on Geoscience and Remote Sensing Volume: 60 Issue: DOI: 10.1109/TGRS.2021.3133582 Published: 2022Abstract:Hyperspectral image (HSI) classification aims to identify categories of hyperspectral pixels. Recently, many convolutional neural networks (CNNs) have been designed to explore the spectrums and spatial information of HSI for classification. In recent CNN-based methods, 2-D or 3-D convolutions are inevitably utilized as basic operations to extract the spatial or spectral-spatial features. However, 2-D and 3-D convolutions are sensitive to the image rotation, which may result in that recent CNN-based methods are not robust to the HSI rotation. In this article, a cross-attention spectral-spatial network (CASSN) is proposed to alleviate the problem of HSI rotation. First, a cross-spectral attention component is proposed to exploit the local and global spectrums of the pixel to generate band weight for suppressing redundant bands. Second, a spectral feature extraction component is utilized to capture spectral features. Then, a cross-spatial attention component is proposed to generate spectral-spatial features from the HSI patch under the guidance of the pixel to be classified. Finally, the spectral-spatial feature is fed to a softmax classifier to obtain the category. The effectiveness of CASSN is demonstrated on three public databases. ? 1980-2012 IEEE.Accession Number: 20215111369025 -
Record 125 of
Title:Design of cooled long-wavelength infrared imaging optical system
Author(s):Shan, Qiu-Sha(1,2); Xie, Mei-Lin(1); Liu, Zhao-Hui(1); Chen, Rong-Li(1); Duan, Jing(1,2); Liu, Kai(1); Jiang, Kai(1); Zhou, Liang(1); Yan, Pei-Pei(1)Source: Chinese Optics Volume: 15 Issue: 1 DOI: 10.37188/CO.2021-0116 Published: January 2022Abstract:Aiming at 640×512 long-wavelength infrared cooled detectors, a cooled long-wavelength infrared optical system was designed to track and detect an infrared target. The optical system adopts the secondary imaging structure to ensure 100% cold-shielding efficiency, and adopts a combination of optical material Ge and ZnS to achieve aberration correction and achromatic design. By introducing the high-order aspheric surface, the high aberration of the system is well-corrected, thus the system structure is simplified. The optical system is composed of 6 lenses. The focal length is 400 mm, the working bands are 7.7~9.3 μm, the field of view is 1.37°×1.10°, and the F-number is 2. The design results show that at a spatial frequency of 33 lp/mm, the MTF of off-axis field of view is more than 0.24, which approaches the diffraction limit and has high imaging quality. In the operating temperature range of ?35~+55 ℃, the focusing lens is used to ensure the imaging quality under high and low temperature environments, which can be used for infrared tracking detection over a wide range of temperatures. Copyright ?2022 Chinese Optics. All rights reserved.Accession Number: 20221011751431 -
Record 126 of
Title:Real-time air turbulence calibration of large aperture camera image quality measurement system
Author(s):Liu, Shangkuo(1,2); Liu, Kai(1); Wang, Zhengfeng(1); Kewei, E.(1); Wang, Tao(1); Zhou, Yan(1); Zhao, Jianke(1); Yao, Baoli(1)Source: Proceedings of SPIE - The International Society for Optical Engineering Volume: 12448 Issue: DOI: 10.1117/12.2638454 Published: 2022Abstract:When measuring image qualities of large aperture cameras, many factors like people moving around, blowing of air conditioners outlets, thermal convection, etc., will give rise to air turbulence (AT). AT mainly induces non-uniform distribution of air components in the image chain of large aperture camera image quality measurement systems, which will lead to variations of system wavefront errors. Thus, AT will introduce errors to measurement results of traditional image quality evaluation methods. Those errors increase with the camera aperture and are usually time-varying. This paper proposes a method to calibrate AT in real time when measuring image qualities of large aperture cameras. A defocused star point target (DSPT) is added to traditional test targets (TTT). The camera under test can capture images of TTT and DSPT simultaneously. The distance between the effective area of TTT and the DSPT is carefully designed so that the corresponding images do not overlap with each other. We calibrate AT induced wavefront errors by processing the DSPT images with phase retrieval method. Experimental results of AT induced wavefront errors calibrated by the proposed method are presented. ? 2022 SPIE.Accession Number: 20224913203720 -
Record 127 of
Title:Implementation of empirical modified generalized Harvey–Shack scatter model on smooth surface
Author(s):Ma, Zhanpeng(1,2); Wang, Hu(1,2); Chen, Qinfang(1,2); Xue, Yaoke(1); Pan, Yue(1,2); Shen, Yang(1,2); Yan, Haoyu(1,2)Source: Journal of the Optical Society of America B: Optical Physics Volume: 39 Issue: 7 DOI: 10.1364/JOSAB.455182 Published: July 2022Abstract:We propose a modified generalized Harvey–Shack model by adding the empirical correction factor related to the scattering angle on the basis of the original theory. The result shows that the modified model reduces the root mean square error (RMSE) from less than 2% to less than 1%, and the relative peak error from less than 50% to less than 20%, which significantly improves the accuracy of scattering prediction. The prediction of the Rayleigh–Rice model is not as good as the Harvey–Shack model. The RMSE of the Rayleigh–Rice model is within 2.5%, and the relative peak error is within 60%. ? 2022 Optica Publishing GroupAccession Number: 20222612272091 -
Record 128 of
Title:Pairwise Comparison Network for Remote-Sensing Scene Classification
Author(s):Zhang, Yue(1,2); Zheng, Xiangtao(1); Lu, Xiaoqiang(1)Source: IEEE Geoscience and Remote Sensing Letters Volume: 19 Issue: DOI: 10.1109/LGRS.2021.3139695 Published: 2022Abstract:Remote-sensing scene classification aims to assign a specific semantic label to a remote-sensing image. Recently, convolutional neural networks (CNNs) have greatly improved the performance of remote-sensing scene classification. However, some confused images may be easily recognized as the incorrect category, which generally degrade the performance. The differences between image pairs can be used to distinguish image categories. This letter proposed a pairwise comparison network (PCNet), which contains two main steps: pairwise selection and pairwise representation. The proposed network first selects similar image pairs and then represents the image pairs with pairwise representations. The self-representation is introduced to highlight the informative parts of each image itself, while the mutual representation is proposed to capture the subtle differences between image pairs. Comprehensive experimental results on two challenging datasets (AID, NWPU-RESISC45) demonstrate the effectiveness of the proposed network. ? 2004-2012 IEEE.Accession Number: 20220211457121 -
Record 129 of
Title:Review of the Development of Interferometric Spectral Imaging Technology (Invited)
Author(s):Hu, Bingliang(1)Source: Guangzi Xuebao/Acta Photonica Sinica Volume: 51 Issue: 7 DOI: 10.3788/gzxb20225107.0751401 Published: July 2022Abstract:Interferometric spectroscopic imaging technology has undergone decades of experience accumulation and technological development. At present，it has extensive and mature applications in the fields of astronomical exploration， atmospheric pollution， water environment monitoring， surface geological mineral exploration，vegetation survey and other fields. Compared with dispersive and filter-type spectral imaging techniques，interferometric spectroscopic imaging technology has the advantages of high resolution，high sensitivity，and high wave number accuracy. According to the type of optical path acquisition method，this paper summarizes the research status of interferometric spectroscopic imaging technology at domestic and abroad from three aspects：time modulation，spatial modulation，and spatiotemporal joint modulation. Then introduces and reviews their representative research results. For time-modulated interferometric spectroscopy imaging，the interferogram acquired by the detector can be seen as a collection of time series. Interference maps are acquired one by one over time. The main advantages of this technique are the high spectral resolution and detection sensitivity. However，this type of optical system requires a continuously moving precision part to produce an optical path difference that changes over time. The main technical difficulty of time-modulated interferometer spectroscopy is how to develop a set of stable，reliable and long-working high-precision moving mirror scanning system. Spatial modulation interferometric spectroscopy records interference information at different cell positions of the detector for different optical path differences of the measured target. A complete interference map of the target can be obtained with a single exposure. This technology fundamentally overcomes the problem of precision moving mirror scanning system in time-modulated spectrometers， and also improves the real-time performance of obtaining spectral information. The essence of spatiotemporal combined modulation interferometer spectroscopy is to insert a transverse shear interferometer into the camera system. Since there is no slit in the front optical system，this type of instrument not only has the characteristics of high detection sensitivity，high stability and high signal-to-noise ratio，but also has the advantages of high throughput. It can be seen that different modulation methods use different optical path structures. Of course，each spectroscopic principle also has its advantages and disadvantages，which can be applied to different application areas. The research of interferometric spectroscopy imaging technology has always attracted much attention. There is no doubt that the emergence of relevant new technologies is often very eye-catching. Over the past three decades，interferometric imaging spectroscopy technology has been rapidly developed in the field of remote sensing，and has gradually become an effective tool for high-resolution remote sensing detection. With the rapid development of detector focal plane array，precision machinery，high-speed data transmission and storage compression，data quantification and computer image processing，the future of spectral imagers will have a large field of view，wide spectral range，high sensitivity，high spectral resolution，high spatial resolution and other performance. Moreover，the technology gradually tends to develop in the direction of new principles，integration，automation，wireless，intelligence，single cylinder and miniaturization. ? 2022 Chinese Optical Society. All rights reserved.Accession Number: 20223612691790 -
Record 130 of
Title:Design of a Ultra-Stable Low-Noise Space Camera Based on a Large Target CMOS Detector and Image Data Analysis
Author(s):Shen, Chao(1,2); Ma, Caiwen(1); Gao, Wei(1)Source: Sensors Volume: 22 Issue: 24 DOI: 10.3390/s22249991 Published: December 2022Abstract:To detect faint target stars of 22nd magnitude and above, an astronomical exploration project requires its space camera’s readout noise to be less than 5e? with long-time working stability. Due to the limitation of satellite, the traditional CCD detector-based camera does not meet the requirements, including volume, weight, and power consumption. Thereby, a low-noise ultra-stable camera based on 9 K × 9 K large target surface CMOS is designed to meet the needs. For the first time, the low-noise ultra-stable camera based on CMOS detector will be applied to space astronomy projects, remote sensing imaging, resource survey, atmospheric and oceanic observation and other fields. In this paper, the design of the camera is introduced in detail, and the camera is tested for several rounds at ?40 °C; it also undergoes further testing and data analysis. Tests proved super stability and that the readout noise is lower than 4.5e?. Dark current, nonlinearity and PTC indicators meet the requirements of the astronomical exploration project. ? 2022 by the authors.Accession Number: 20225213308841 -
Record 131 of
Title:Comprehensive design analysis and verification of space-based short-wave infrared coded spectrometer via curved prism dispersion
Author(s):Jia, Xin-Yin(1,2); Li, Xi-Jie(1); Hu, Bing-Liang(1); Li, Li-Bo(1); Wang, Fei-Cheng(1); Zhang, Zhao-Hui(1); Yang, Ying(1); Ke, Shan-Liang(1); Zou, Chun-Bo(1); Liu, Jia(1); Li, Si-Yuan(1)Source: Applied Optics Volume: 61 Issue: 8 DOI: 10.1364/AO.449320 Published: March 10, 2022Abstract:The spaceborne dispersive spectrometer is widely used in environmental, resource, and ocean observations. The coded spectrometer has higher energy advantages than the dispersion spectrometer, so it has great application prospects. In the current study, we developed an off-axis short-wave infrared coded optical system (SICOS) based on curved prism dispersion, and we further explored the design and optimization of the SICOS structure. Finite element analyses of a space-based short-wave infrared coded spectrometer based on curved prism dispersion (SSICS-CPD), including static simulation, modal analysis, sinusoidal vibration mechanical analysis, and random vibration mechanical analysis, were carried out. Simulation results showed that the SICOS support structure had excellent mechanical and thermal stability. As off-axis optical systems cannot meet the requirements of optical position accuracy through centering processing, a point source microscope and three-coordinate measuring machines were employed to complete the high-precision and rapid assembly of the SSICS-CPD. In addition, verification tests of surface shape error, stress relief, random vibration, and optical design parameters were carried out to validate the high stability and imaging performance of the SSICS-CPD. Results showed that the average modulation transfer function in the full field was 0.43 at 16.67 lp/mm, the spectral smile was ? 2022 Optica Publishing Group.Accession Number: 20221111784758 -
Record 132 of
Title:Generation of subcycle isolated attosecond pulses by pumping ionizing gating
Author(s):Wu, Zhaohui(1); Peng, Hao(2); Zeng, Xiaoming(1); Li, Zhaoli(1); Zhang, Zhimeng(1); Cao, Huabao(3); Fu, Yuxi(3); Wang, Xiaodong(1); Wang, Xiao(1); Mu, Jie(1); Zuo, Yanlei(1); Riconda, C.(4); Weber, S.(5); Su, Jingqin(1)Source: arXiv Volume: Issue: DOI: 10.48550/arXiv.2212.06599 Published: December 13, 2022Abstract:We present a novel approach named as pumping ionizing gating (PIG) for the generation of isolated attosecond pulses (IAPs). In this regime, a short laser is used to ionize a pre-existing gas grating, creating a fast-extending plasma grating(FEPG) having an ionization front propagating with the velocity of light. A low-intensity long counterpropagating pump pulse is then reflected by a very narrow region of the ionization front, only where the Bragg conditions for resonant reflection is satisfied. Consequently, the pump reflection is confined within a sub-cycle region called PIG, and forms a wide-band coherent IAP in combination with the frequency upconversion effect due to the plasma gradient. This approach results in a new scheme to generate IAPs from long picosecond pump pulses. Three-dimensional (3D) simulations show that a 1.6-ps, 1-μm pump pulse can be used to generate a 330 as laser pulse with a peak intensity approximately 33 times that of the pump and a conversion efficiency of around 0.1%.These results highlight the potential of the PIG method for generating IAPs with high conversion efficiency and peak intensity. ? 2022, CC BY.Accession Number: 20220465973