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Record 361 of
Title:Design of wide-spectrum directed multispectral imaging system with visible light
Author(s):Shan, Qiu-Sha(1); Liu, Kai(1); Yan, Pei-Pei(1); Duan, Jing(1); Jiang, Kai(1); Zhou, Liang(1)
Source: Proceedings of SPIE - The International Society for Optical Engineering Volume: 10840 Issue: DOI: 10.1117/12.2513372 Published: 2019
Abstract:In this paper, a visible spectral multi-spectral imaging system with spectral resolution better than 14nm is designed. The system uses dual Amici dispersive prisms as the optical splitters to provide the parallel beam dispersion with the widen spectral range. When designed, the fore-Telescope?€collimating lens and imaging objective lens adopt telecentric structure to facilitate pupil matching, and the directed characters of dual Amici prisms make the coaxial design realized. The spectral range is 400nm-900nm, the relative aperture is 1/2.4, the optical design software CodeV is used for ray tracing and optimization of the spectral imaging system, and the design results are analyzed. The analysis result show that the optical modulate transfer function has reached 0.75 or more in each spectral segment of the optical system, the spectral resolution is better than 14nm, the smile and keystone are better than 5um, meeting the design requirements. The system has the features of widen spectral range, the smaller of the smile and keystone. ? 2019 SPIE.
Accession Number: 20190706497348
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Record 362 of
Title:A fault injection system for space imaging application
Author(s):Wang, Jinqiao(1,2); Duan, Yongqiang(1); Ma, Tengfei(1)
Source: Proceedings of SPIE - The International Society for Optical Engineering Volume: 11335 Issue: DOI: 10.1117/12.2544241 Published: 2019
Abstract:The SRAM-based FPGAs are widely used in space imaging system because of their reprogramming advantages. However, designers must be concerned with the effect of single event upset(SEU) on FPGA configuration memory in the space application. To evaluate the performance of SRAM-based FPGA against SEU, simulating SEU fault injection test is a common method. This paper mainly studies the method of fault injection test and the structure of test platform. The data of CCD driving timing is flipped bit by bit on the test platform. And finally count the fault rate is 1.25%, then taking about 240ms to repair the fault. ? 2019 SPIE.
Accession Number: 20200308054548
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Record 363 of
Title:Wide-field and large aperture optical system design for ground-based photoelectric detection
Author(s):Yan, Peipei(1); Yang, Yongqing(1); She, Wenji(1); Liu, Kai(1); Jiang, Kai(1); Duan, Jing(1); Shan, Qiusha(1)
Source: Proceedings of SPIE - The International Society for Optical Engineering Volume: 10837 Issue: DOI: 10.1117/12.2513247 Published: 2019
Abstract:Detection and recognition of space objects with ground-based photoelectric systems is one of the major technical ways for space situational awareness. During the past thirty years, there has been significant development of optical telescopes dedicated to wide-field surveys of time-dependent deep space phenomena, slow-moving near-earth objects (NEOs) and fast-moving earth-orbiting space debris. While telescope fields of view have gradually increased, a single technical approach has not emerged as the dominant design. To design an effective wide-field telescope for sky survey or space surveillance, It is necessary to carefully match the characteristics of the optical system (layout, aperture, focal ratio and modulation transfer function) with those of the observing site (sky brightness, transparency, seeing and elevation), the detector (pixel pitch, quantum efficiency, read rate and read noise), and the observing program (target brightness, target motion, observing strategy and feature extraction software). In this paper, we design a telescope with wide field of view (≥2.5°×3.5°) and large aperture (1.1m). The focal length of the system is 1.5m, F/# is 1.36. Because of the small Fnumber and wide field of view, we choose the prime focus corrector structure which has single mirrors with refractive prime focus correctors. Moreover, the especial requirements of the Modulation Transfer Function (MTF), spot, energy concentration, and distortion etc. are all satisfied. ? 2019 SPIE.
Accession Number: 20190506432470
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Record 364 of
Title:Thermal vacuum optical performance test system for space laser communication terminal
Author(s):Xue, Xun(1,2,3); Zhao, Jianke(1); Zhang, Chunmin(2,3); Liu, Shangkuo(1); Kewei, E.(1); Li, Kun(1); Wang, Zhengfeng(1); Li, Jing(1); Zhang, Jie(1); Hu, Dandan(1); Guo, Yi(1)
Source: Proceedings of SPIE - The International Society for Optical Engineering Volume: 11052 Issue: DOI: 10.1117/12.2522000 Published: 2019
Abstract:In order to ensure the on-orbit performance of space laser communication terminal(SLCT), the optical performance test under thermal vacuum conditions must be completed on the groud. In this paper, according to the requirements of SLCT, thermal vacuum optical performance test system was designed and developed. Its main testing capabilities include the divergence angle, polarization state, wave aberration, transmission power. Several SLCTs were tested by the system, the results show that the overall performance of the test system is stable and the thermo-optical test of SLCT can be completed well. ? 2019 SPIE.
Accession Number: 20190806534745
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Record 365 of
Title:Optical system design of dual-band observation and imaging
Author(s):Hou, Pan(1,2); Zhu, Qing(1); Li, Ruichang(1,2); Ma, Zhanpeng(1,2)
Source: Proceedings of SPIE - The International Society for Optical Engineering Volume: 11341 Issue: DOI: 10.1117/12.2541899 Published: 2019
Abstract:In this paper, a dual-band (visible light and SWIR) observation and imaging optical system is proposed. The system can acquire the optical characteristics of the target in the range of 900nm-1700nm by imaging. SWIR imaging not only can get the infrared characteristics of the target, but also has the ability of anti-camouflage and through-fog. It makes up for the deficiency of visible light imaging. The integrated system of visible light and SWIR can be widely used in military monitoring, forest fire prevention, geodesy and other fields, and has high practical values. The integrated system shares the front group of telescopic objective and shares the field of view. The visual observation system working in the visible band, the diameter of the entrance pupil is 24mm, the diameter of the exit pupil is 6mm, the distance of the exit pupil is more than 20mm, and the visual magnification is-4×. The SWIR imaging system working in 900nm-1700nm, and the diameter of the pupil is 24mm, and the focal length is 117.3mm. The field of view is for the two systems. The design and analysis results show that the system has dual-channel imaging of visible light and SWIR with common field of view, which can obtain clear visual images and digital images. The quality of the visual system and the imaging system meet the needs. ? 2019 SPIE.
Accession Number: 20200408063334
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Record 366 of
Title:Experimental and theoretical analysis of the effect of packaging induced thermal stress on high-power laser diode arrays
Author(s):Zhang, Hongyou(1,2); Zah, Chung-En(4); Liu, Xingsheng(2,3,4)
Source: Proceedings of SPIE - The International Society for Optical Engineering Volume: 10900 Issue: DOI: 10.1117/12.2506212 Published: 2019
Abstract:High power laser diodes have been widely utilized in many fields, like industry, scientific research, military and medical treatment, etc. However, thermal stress induced by packaging process due to CTE-mismatch between chip and heat-sink is the main source causing near-field non-linearity along laser bar (also known as "SMILE"), decreasing the degree of polarization (DoP), broadening spectrum, and degrading the lifetime of laser diode array (LDA). In this paper, the effect of packaging induced thermal stress on high power laser diode arrays was studied theoretically and experimentally. The FEM simulation and photoluminescence (PL) experimental results showed the difference of packaging induced thermal stress based on different packaging structures. Spectrally resolved spectrum of LDA showed the packaging induced stress is highest in the middle and rapidly drops near both ends of laser bar, in agreement with our theoretical simulation, resulting in spectral broadening due to blue shifting the lasing wavelength of the center emitter more than the edge emitters. ? COPYRIGHT SPIE. Downloading of the abstract is permitted for personal use only.
Accession Number: 20192307012270
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Record 367 of
Title:GETNET: A general end-to-end two-dimensional CNN framework for hyperspectral image change detection
Author(s):Wang, Qi(1); Yuan, Zhenghang(2); Du, Qian(3); Li, Xuelong(4)
Source: arXiv Volume: Issue: DOI: null Published: May 5, 2019
Abstract:Change detection (CD) is an important application of remote sensing, which provides timely change information about large-scale Earth surface. With the emergence of hyperspectral imagery, CD technology has been greatly promoted, as hyperspectral data with high spectral resolution are capable of detecting finer changes than using the traditional multispectral imagery. Nevertheless, the high dimension of hyperspectral data makes it difficult to implement traditional CD algorithms. Besides, endmember abundance information at subpixel level is often not fully utilized. In order to better handle high dimension problem and explore abundance information, this paper presents a General End-to-end Two-dimensional CNN (GETNET) framework for hyperspectral image change detection (HSI-CD). The main contributions of this work are threefold: 1) Mixed-affinity matrix that integrates subpixel representation is introduced to mine more cross-channel gradient features and fuse multi-source information; 2) 2-D CNN is designed to learn the discriminative features effectively from multi-source data at a higher level and enhance the generalization ability of the proposed CD algorithm; 3) A new HSI-CD data set is designed for objective comparison of different methods. Experimental results on real hyperspectral data sets demonstrate the proposed method outperforms most of the state-of-the-arts. Copyright ? 2019, The Authors. All rights reserved.
Accession Number: 20200502188
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Record 368 of
Title:A novel baffle based on horn tube effect
Author(s):Wu, Liquan(1,2); Wang, Hu(1)
Source: Proceedings of SPIE - The International Society for Optical Engineering Volume: 11341 Issue: DOI: 10.1117/12.2543353 Published: 2019
Abstract:Stray light severely affecting the performance of the spatial optical systems,the baffle as a kind of major measure that can effectively suppress stray light.Optimizing the internal structure of the baffle and choosing the appropriate material for the baffle are of great significance for improving the performance of the space optical systems.This paper proposes a structure design scheme of novel baffle based on the horn tube effect.This paper establishes a mathematical model for the structure of the horn tube, and uses MATLAB software to carry out the programming simulation to analyze the influence of different structural parameters on the number of reflections of the inner wall of the horn tube under different off-axis angles of the light source.The horn tube was applied as the structure of stray light suppression to a cylindrical baffle, and a three-dimensional model was built by using Solidworks software and imported into TracePro software to analyze the capability of suppressing stray light.Comparing the vertical vane with the horn tube, the results show that the horn tube as the vane has the better effect to suppress stray light,increased efficiency by nearly 50%. ? 2019 SPIE.
Accession Number: 20200408063350
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Record 369 of
Title:High-power low-smile vertically-stacked laser diode based on microchannel cooling
Author(s):Zhang, Hongyou(1,2,4); Cai, Lei(4); Zah, Chung-En(4); Liu, Xingsheng(2,3,4)
Source: Proceedings of SPIE - The International Society for Optical Engineering Volume: 11182 Issue: DOI: 10.1117/12.2536518 Published: 2019
Abstract:Large smile, the emitters in a laser diode are vertically displaced, is always a big obstacle to affect the directly application of high power laser diode. In this report, a symmetrical structure, that bonding two submounts on the top and bottom of heat sink to control the smile effect by balancing the packaging induced stress, is designed. A cm bar with less than 1 um smile value delivering more than 200W continuous wave (CW) mode output power with power conversion efficiency (PCE) 65% is reported. The lifetime can reach more than 20000 hours. We also report the applications of high power and low smile vertically stacked laser bars, like forming a wider line for glass surface treatment and a rectangular beam for cladding. A 2x14mm2 rectangular beam was built with 32 bars vertical stack to produce 6kW CW mode output power with a beam uniformity of more than 80%. ? 2019 SPIE.
Accession Number: 20200308054710
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Record 370 of
Title:A method for optimizing and designing high isolation level Cassegrainian optical antenna
Author(s):Zhou, Shao-Pan(1,2); Xue, Bin(1); Yang, Jian-Feng(1); Liu, Sheng-Run(1,2); Chen, Guo-Qing(1,2)
Source: Proceedings of SPIE - The International Society for Optical Engineering Volume: 10838 Issue: DOI: 10.1117/12.2505379 Published: 2019
Abstract:In order to reduce the optical intensity of backscattering lights of the Cassegrainian optical antenna in the optical system of the laser communication terminal and improve the optical isolation of laser communication system, this paper proposes a method for designing high isolation level Cassegrainian optical antenna by increasing the characteristic value of the optical intensity of backscattering lights E/N. The method aims to improve the optical antenna isolation through reducing the optical intensity of backscattering lights along the incident optical path based on analyzing the theoretical model of the optical intensity of backscattering lights BRDF. A Cassegrainian optical antenna for laser communication is designed in this paper, and the method is used to optimize the isolation of this optical antenna by custom operands in ZEMAX. Then using TracePro software builds the optical structure model of this optical antenna before and after optimization, simulate the optical intensity of backscattering lights of each model, calculate and analyze the isolation of each model by using simulation data respectively. It is show that the backscattering rate of the system decreases from 0.0011956 to 0.00007515, and the isolation decreases from-29.224dB to-41.24dB. Optimization has improved the isolation 12.017dB of the optical system through use the method. ? 2019 COPYRIGHT SPIE. Downloading of the abstract is permitted for personal use only.
Accession Number: 20190506430103
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Record 371 of
Title:2 μ m vector mode-locked pulses from Tm:Y2O3 ceramics laser
Author(s):Zhou, Wei(1,2); Huang, Haitao(1,2); Chen, Xiang(1,2); Wang, Jingru(1,2); Xu, Rui(1,2); Wang, Haotian(1,2); Zhao, Yongguang(1,2); Tang, Dingyuan(1,2); Wang, Yishan(3); Shen, Deyuan(1,2)
Source: Laser Physics Volume: 29 Issue: 4 DOI: 10.1088/1555-6611/aaffc4 Published: February 27, 2019
Abstract:We report on stable passively mode-locked (ML) pulses with Tm:Y2O3 ceramics operating at a 2 μm wavelength range for the first time. With a SESAM, synchronous ML pulses with dual-wavelengths are obtained, with a typical pulse width of 40 ps, a maximum output average power of 240 mW and a pulse repetition rate of ～124 MHz. The output pulses were further proved to be stable polarization-locked vector pulses. To our knowledge, this is also the first observation of vector pulses in 2 μm ML solid-state oscillators. ? 2019 Astro Ltd.
Accession Number: 20191806859828
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Record 372 of
Title:Design of visible light / LWIR dual-band common aperture imaging optical system
Author(s):Ma, Zhanpeng(1,2); Wang, Hu(1,2); Shen, Yang(1,2); Wang, Fang(1,2); Xue, Yaoke(1)
Source: Proceedings of SPIE - The International Society for Optical Engineering Volume: 11341 Issue: DOI: 10.1117/12.2541742 Published: 2019
Abstract:Dual-band imaging system can effectively improve the detection and identification capability for airborne camera. To ensure the system with compact structure and without increasing the complication of the design, a catadioptric system is proposed as an alternative where the visible light and long-wave infrared (LWIR) share the mutual aperture and adding a dichroic beam splitter between the primary and secondary mirrors enables simultaneous imaging of the two bands. The common aperture is achieved by sharing a modified Cassegrain reflection structure in both bands. The entrance pupil diameter for the two bands is 148mm and their field of view (FOV) is 3°. The visible light works in the range of 0.51/40.8μm and the focal length is 304.2mm with 2048×2048 detector, and the pixel size is 5.5μm. The LWIR works in the range of 8μm1/414μm and the focal length is 205.3mm with 1024×768 infrared detector, and the pixel size is 14μm. The system aberration is well corrected in two bands and for the performance analysis of the system in the temperature range of 20±5?C, the design results can meet the requirements. ? 2019 SPIE.
Accession Number: 20200408063332
