2019
2019
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Record 313 of
Title:Similarity Constrained Convex Nonnegative Matrix Factorization for Hyperspectral Anomaly Detection
Author(s):Zhang, Wuxia(1,2); Lu, Xiaoqiang(1); Li, Xuelong(3,4)Source: IEEE Transactions on Geoscience and Remote Sensing Volume: 57 Issue: 7 DOI: 10.1109/TGRS.2019.2893116 Published: July 2019Abstract:Hyperspectral anomaly detection is very important in the remote sensing domain. The representation-based anomaly method is one of the most important hyperspectral anomaly detection methods, which uses reconstruction errors (REs) to detect anomalies. REs are affected by the basis matrix and its corresponding coefficient matrix. Mixed pixels exist because of the low-spatial resolution of hyperspectral images. The RE is not large enough to correctly distinguish the pixel difficult to classify when the basis matrix is composed of pixels. Moreover, its corresponding coefficients cannot indicate whether pixels are pure or mixed and the abundances of mixed pixels. To address the above-mentioned problems, endmembers referring to pure or relatively pure spectral signatures are explored to build the basis matrix. The RE based on the basis matrix of endmembers is much larger for the anomalous pixel difficult to correctly classify. Furthermore, its corresponding coefficient matrix of endmembers has physical meanings. Hence, a novel hyperspectral anomaly detection based on similarity constrained convex nonnegative matrix factorization is proposed from the perspective of endmembers for the first time. First, convex nonnegative matrix factorization (CNMF) is employed to obtain endmembers of background. Then, CNMF is constrained by the similarity regularization that considers different contributions of endmembers to the pixel under test to acquire the more accurate and meaningful coefficient matrix. Finally, anomalies are detected by calculating REs. The proposed algorithm is verified on both simulated and real data sets. Experimental results show that our proposed algorithm outperforms other state-of-the-art algorithms. ? 1980-2012 IEEE.Accession Number: 20192707144263 -
Record 314 of
Title:Target detection method for small defects in ink area of planar glass element
Author(s):Qi, Wenbo(1); Wang, Zhengzhou(1); Wang, Li(1); Tan, Meng(1); Wei, Jitong(1)Source: Proceedings of SPIE - The International Society for Optical Engineering Volume: 11342 Issue: DOI: 10.1117/12.2542893 Published: 2019Abstract:In the detection of small and weak defect targets in ink area of planar glass element of a mobile phone, using linear array camera with dark field illumination and line-by-line scanning imaging system will result in the size of image (30720 ?16384) much larger than the size of small defect targets (3 pixels). At the same time, because the stains are located in the ink area, the contrast between the defect target and the background of the ink area could be very low. This will lead to the weak defect targets in the ink area could not be detected quickly and effectively using the common target detection method. In order to solve this problem, a detection method of small and weak defects in the ink area of planar glass element based on self-correlation template matching and one-dimensional maximum entropy is proposed in this paper. Firstly, the large-scale image is first clipped, and the character information in the ink area is recognized and fixed position using the self-correlation template matching algorithm. The character and Logo information in the ink area are clipped according to the positioning results. Secondly, the processed image is clipped twice and binarized by the OTSU method. BLOB technology is used to select the largest white area as the ink area in the second clipping image. Thirdly, Sobel operator is used to detect the edge of the ink area, and the transitional area with the width of 100 pixels on the edge of the ink area is clipped, so the clipping image of the ink area which only contained valid small and weak defect targets is obtained. Finally, One-dimensional maximum entropy algorithm is used to separate the defect targets from real ink area, and the weak and small defect targets are recognized and detected by BLOB technology. The experimental results show that the method solves the problem of detecting the small and weak defects in the ink area of the planar glass element with fast recognition speed and high detection accuracy. It can be applied in the process of detecting the quality and cleanliness of planar glass element, and has great significance for improving the quality and efficiency of mobile phone production and assembly. ? 2019 SPIE.Accession Number: 20200308047025 -
Record 315 of
Title:Mineral Element Abundance Identification Based on LIBS Emission Line Selection by Loading Space Distance of Principal Component Analysis
Author(s):Guo, Kai-Chen(1,2); Wu, Zhong-Chen(1,2); Zhu, Xiang-Ping(3); Ling, Zong-Cheng(1,2); Zhang, Jiang(1,2); Li, Yun(1,2); Qian, Mao-Cheng(1,2)Source: Guangzi Xuebao/Acta Photonica Sinica Volume: 48 Issue: 10 DOI: 10.3788/gzxb20194810.1030002 Published: October 1, 2019Abstract:The concentration and laser-induced breakdown spectroscopy data of 64 pre-flight calibration samples, published by the ChemCam team, were used as objects of research. Principal component analysis loading space distance method was used to analyze the target element, the most sensitive laser-induced breakdown spectral line of the target element was selected, and the mineral element species and abundance were identified with the identification accuracy up to 92.8% based on this method. The result shows that principal component analysis loading space distance can be used as a criterion to obtain the critical element information of minerals element abundance before, if aim to serve for, quantitative analysis. This study reduces the difficulty in rock/mineral classification and is beneficial to unknown minerals analysis, which offers an effective identification strategy for the Martian surface rock type analysis. ? 2019, Science Press. All right reserved.Accession Number: 20194707721071 -
Record 316 of
Title:Simple method for simultaneous long-term stabilization of relative timing and carrier-envelope phase in waveform synthesis
Author(s):Huang, Pei(1,2,3); Fang, Shaobo(2,3); Gao, Yitan(2,3); Zhao, Kun(2,3); Hou, Xun(1,3); Wei, Zhiyi(2,3)Source: Applied Physics Letters Volume: 115 Issue: 3 DOI: 10.1063/1.5083239 Published: July 15, 2019Abstract:We present an f-to-2f interferometry method to simultaneously measure and control the relative timing (RT) and carrier-envelope phase (CEP) of an arbitrarily tailored optical-field waveform. Long-term stabilization of the phase-locking system results in a CEP stability of 280 mrad and a RT stability of 110 attosecond over 8 h at a repetition rate of 1 kHz. The synthesized optical field characterized by a transient-grating frequency-resolved optical gating delivers 3.8-fs near single-cycle waveforms. This technique constitutes a versatile tool for coherent pulse synthesis, which can be applied in experiments using a dual-color light field for high-harmonic generation and attosecond timing precision pump-probe spectroscopy. ? 2019 Author(s).Accession Number: 20193007227356 -
Record 317 of
Title:Optical system design and manufacture for a 1U CubeSat
Author(s):Pang, Zhihai(1); Song, Zongxi(1); Sun, Zhonghan(1); Cheng, Pengfei(1); Dan, Lijun(1); Li, Wei(1); Fan, Xuewu(1)Source: Proceedings of SPIE - The International Society for Optical Engineering Volume: 11341 Issue: DOI: 10.1117/12.2542219 Published: 2019Abstract:Optical design of a small reflecting telescope for use in a 1U CubeSat mission is reported in this study. A Ritchey-Chretien with field correction lens type telescope for earth observation techniques is adopted in this design. The primary mirror and secondary mirror are circular apertures with 70-mm and 21-mm in diameter. The effective focal length is 390-mm operated at 600-km altitude. A commercial 2560 × 2160 CCD image sensor CIS2521 with a pixel size of 6.5 μm is applied, which capture a 25km swath area. The ground resolution is better than 10m for CubeSat application. The MTF is expected to be about 0.3 at Nyquist frequency at 77lp/mm. The tolerance analysis is performed for further understanding on fabrication and assembly errors. In order to reduce the telescope size, the optical system uses a reflective optical system, and the circuit board is arranged behind the system and above. The telescope envelope size(all contained) is less than 96mm × 90mm × 90mm and the weight is approximately 600g. At present, the aspherical primary mirror has completed the processing and assembly. ? 2019 SPIE.Accession Number: 20200408063337 -
Record 318 of
Title:Angular micro-vibration test of an agile satellite high resolution camera based on liner accelerometer
Author(s):Cui, Kai(1); Zheng, Zhiqi(1); Gao, Xiong(1); Yang, Yongqing(1); Li, Zhiguo(1); Li, Shuxiu(1)Source: Proceedings of SPIE - The International Society for Optical Engineering Volume: 11052 Issue: DOI: 10.1117/12.2521437 Published: 2019Abstract:The angular micro-vibration of a high resolution camera mounting on an agile satellite was achieved based on pairs of liner accelerometers alignment and numerical integration method. Three pairs of sensors were mounted at different portion of the satellite for studying the structure transfer character, including the Reaction Wheel (RW)interface, the camera interface and the camera tail. The results showed that the RW original micro-vibration standard deviation (STD) output acquired at the RW interference was 1.63μrad at RW 400rpm and increased to 2.43μrad when the RW speed up to 800rpm. When transferring from RW to the camera interface, the angular vibration response STD was attenuated to 0.31μrad@400rpm and 0.27μrad@800rpm, and finally to the camera tail the angular vibration response STD became 0.31μrad@400rpm and 0.30μrad@800rpm. We can see that the satellite-camera structure has a good attenuation effect on the micro-vibration, the output angular micro-vibration STD is about 0.31μrad with an input of 1.63μrad～2.43μrad. the stiffness of the camera is pretty good, ensuring that the micro-vibration STD difference between the camera flange and the camera tail is smaller 0.03μrad. In addition, we found that the FOGs useful bandwidth wasn't insufficient when acquiring about 340Hz main frequency vibration signal in our case, even though a higher stiffness flange was recommended which connecting the FOG and camera. ? 2019 SPIE.Accession Number: 20190806535037 -
Record 319 of
Title:Design and fabrication of CGH for 820mm diameter tertiary mirror surface figure testing without center hole
Author(s):Pang, Zhihai(1); Feng, Liangjie(1); Ding, Jiaoteng(1); Fan, Xuewu(1); Ma, Zhen(1)Source: Proceedings of SPIE - The International Society for Optical Engineering Volume: 10840 Issue: DOI: 10.1117/12.2504889 Published: 2019Abstract:Computer-generated hologram (CGH) is an effective way to compensate wavefront aberration in null test of aspheric surfaces and freeform surfaces. Our strategies of CGH design for 820mm diameter tertiary mirror surface figure testing are presented, and an experiment demonstrating the compensation test results of CGH is reported. We design a CGH including two sections on the same substrate in order to align the CGH to the incident wavefront: main section for compensating wavefront in null test, alignment section for adjusting the relative position between CGH and interferometer. Because there is no center hole in the mirror, in order to isolate different orders of diffraction, we used tilt carrier to make different orders of diffraction come to focus at different position perpendicular the axis to avoid ghost reflections. ? 2019 SPIE.Accession Number: 20190706497366 -
Record 320 of
Title:Ultra-wide field multispectral integrated spatial optical system design
Author(s):Ren, Zhi-Guang(1,2); Li, Xu-Yang(1); Ni, Dong-Wei(1)Source: Proceedings of SPIE - The International Society for Optical Engineering Volume: 11341 Issue: DOI: 10.1117/12.2542191 Published: 2019Abstract:As the spatial resolution, temporal resolution, and spectral resolution performance of space remote sensing optical systems continue to increase, the demand for performance in large fields of view, large relative apertures, and multiple spectral segments is increasing. Aiming at the requirements above requirements, an off-axis common aperture space remote sensing optical systems was designed whicn is based on PW method and Gaussian formula. The system adopts the combination of off-axis two-mirror, beam splitter and refractive optical system. The relative aperture of the visible spectrum is 1/8, field of view is 0.72°, working band is 450～850nm, the focal length is 320mm, and detector pixel size is 5.5μm×5.5μm; The relative aperture of detection system is 1/8, field of view is 9.8°, working band is 3～5μm, focal length is 80mm, and detector is 17μm×17μm. The modulation transfer function of imaging system is about 0.5 at 90.9lp/mm; energy distribution of detection system is higher than 80% at 34μm, confusion spot size is smaller than 34μm. The PW method is used to solve the structural parameters of the off-axis two-mirror system, zoom-in and zoo-out system are respectively spliced, the front off-axis two mirror system is shared, asemi-reverse and semi-transparent film is placed behind the secondary mirror.The optical system adopts a zoom-in lens group to realize imaging system, and adopts a zoom-out lens group to realize infrared detection system. The spatial remote sensing optical system is combined to meet the requirements, the optical system is small in size, light in weight and compact in structure. ? 2019 SPIE.Accession Number: 20200408063335 -
Record 321 of
Title:The study of free form optical elements corrected aberrations of optical system
Author(s):Pang, Zhihai(1); Zou, Gangyi(1); Fan, Xuewu(1); Ma, Zhen(1); Chen, Qinfang(1)Source: Proceedings of SPIE - The International Society for Optical Engineering Volume: 10837 Issue: DOI: 10.1117/12.2504891 Published: 2019Abstract:Based on the wavefront aberration theory and the coordinates transform, the free form optical induced aberration's characteristic of optical system has been analyses in this paper. The optical wavefront error and the free form surface can be express as Fringe Zernike polynomial; the free form optical on the surface (Stop or Entrance pupil or Exit pupil) affects all the field angles equally. If the surface is not the pupil of optical system, the aberration observed is different from the free form itself because the footprint of the beam for an off-axis field point only covers part of the surface. For the Fringe Zernike surface figure on a surface not at pupil, it will transform into lower order Fringe Zernike aberration in the optical system, the relationship between different Fringe Zernike aberration and field is different, and the location zero for the lower aberration always reside at the center of the field of view. ? 2019 SPIE.Accession Number: 20190506432474 -
Record 322 of
Title:Design of polarization imaging optical system with divided aperture
Author(s):Ren, Zhi-Guang(2); Li, Xu-Yang(1); Ni, Dong-Wei(1); Yang, Ming-Yang(1)Source: Proceedings of SPIE - The International Society for Optical Engineering Volume: 10838 Issue: DOI: 10.1117/12.2505016 Published: 2019Abstract:As a new kind of optical imaging technology, polarimetric imaging can be able to identify the target that may be difficult to conventional ones and can reduce the influence of stray and complex environment. It can efficiently increase the detection dimension of the information and increase capability of target imaging and recognition by imaging the polarization properties of the optical wave. The dissertation researches a type of simultaneous polarization imaging optical system with divided aperture. This system is adopted the identification system of polarization and morphological feature, which can improve the ability of space target classification and recognition. It also can be used as a space-based space target imaging system, which can be used for the classification and recognition of space target. Polarization optical system is adopted the structure mode of two-mirror reflecting systems and field correction mirror, pupil division and four zoning registration scheme of array CCD detector. The system technical parameters are F#/12.5, EFL 1500mm, FOV 0.47°. The size of CCD pixel is 12μm×12μm. The system can detect the light of 0°/45°/90° and visible light for 450-850 nm spectrum. It reached the conclusion that optical system imaging quality is close to the diffraction limit at the Nyquist frequency 41.70lp/mm though simulation test, the system can meet the imaging requirements. ? 2019 COPYRIGHT SPIE. Downloading of the abstract is permitted for personal use only.Accession Number: 20190506430679 -
Record 323 of
Title:Micro-vibration test of a reaction wheel after the mechanical test and transferring property through a shafting
Author(s):Cui, Kai(1); She, Wenji(1); Gao, Xiong(1); Li, Zhiguo(1); Zheng, Zhiqi(1); Wang, Huan(1)Source: Proceedings of SPIE - The International Society for Optical Engineering Volume: 11068 Issue: DOI: 10.1117/12.2523186 Published: 2019Abstract:The spacecraft micro-vibration restricts the smoothness of satellite-born pointing assembles, especially for space-based laser communication, it may cause more capacity loss. A precision shafting is often the key component, connecting the satellite and the optical antenna, and transferring micro-vibration from the satellite bus to the above payload. The oscillation characteristics of the Reaction Wheel(RW) subjected to mechanical tests was implemented via pairs of liner accelerometers and acquisition system, then the micro-vibration transfer property through shafting were studied. The results showed that the RW vibration standard deviation (STD) magnified about 5 times to 30mg～50mg in time domain after the mechanical test, the FFT analysis in frequency domain showed the vibration response frequency was spurious, but the main frequency of about 430Hz and 860Hz which matched the frequency multiplication of the frequency the RW bearing balls passing the point defects in the bearing inner part. The liner acceleration and angular velocity was almost direct ratio to the RW speed, and the RW tangential vibration seemed to be more sensitive to the speed. The space used precision shafting showed perfect attenuation for a high frequency angular vibration transferring, the attenuation ratio was about 70%. ? COPYRIGHT SPIE. Downloading of the abstract is permitted for personal use only.Accession Number: 20192106969512 -
Record 324 of
Title:Research on underwater high-speed blue-green optical communication technology based on blue LD array
Author(s):Han, Yi(1,2); Zheng, Yunqiang(1); Shi, Kui(1); Wang, Tao(1); Xie, Xiaoping(1); Meng, Jiacheng(1); Wang, Wei(1); Duan, Tao(1); Han, Biao(1); Wan, Rengang(2); Sun, Kelin(3)Source: Proceedings of SPIE - The International Society for Optical Engineering Volume: 11068 Issue: DOI: 10.1117/12.2523916 Published: 2019Abstract:In underwater wireless optical communication (UWOC), one of the key technologies is to generate high-speed communication signal for transmitter. In this paper, we designed such transmitter based on laser diode (LD) arrays, which is composed of three LDs with central wavelength 450nm. The modulation format is non-return-to-zero on-off keying (NRZ-OOK) with data rate up to 50Mbps. Using such transmitter, we established a point-to-point underwater wireless optical communication link in an experimental tank with 20m length, 20m width and 14 depth. The experimental results show that the maximum error-free data rate of the system can reach 50Mbps with 10.7m transmission distance, while the maximum error-free transmission rate is 30Mbps with 14.7m transmission distance. These results verify the feasibility of the LD-based modulation scheme for high-speed UWOC applications. ? COPYRIGHT SPIE. Downloading of the abstract is permitted for personal use only.Accession Number: 20192106969526