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Record 301 of
Title:All-fiber polarization interference filter based uniform multiwavelength erbium-doped fiber laser
Author(s):Wang, Hushan(1,2,4); Zhao, Fengyan(1,2,4); Yan, Zhijun(1,3); Hong, Xiaohu(1); Song, Jiazheng(1,2); Zhou, Kaiming(1); Zhang, Ting(1,2); Zhang, Wei(1); Wang, Yishan(1,4)
Source: Laser Physics Volume: 29 Issue: 5 DOI: 10.1088/1555-6611/ab0d0e Published: April 4, 2019
Abstract:We demonstrate a compact and stable room-temperature multiwavelength erbium doped fiber laser by employing 45° tilted fiber gratings based on an all-fiber polarization interference filter. Benefiting from the filter, the channel number, linewidth, uniformity and stabilization of the multiwavelength laser are greatly improved. The filter also works as a functional polarizing device in a nonlinear polarization rotation, leading to the multiwavelength operation. Instead of a highly nonlinear fiber, the single mode fiber is used to provide enough linearity and to reduce the splice loss. More than 80 wavelengths (within a 3 dB bandwidth), lasing with a linewidth of 0.03 nm and a signal-to-noise ratio of 33 dB, are obtained. The wavelength spacing of 0.164 nm agrees with the channel spacing of the filter, and can be flexibly controlled by adjusting the length of the filter. ? 2019 Astro Ltd.
Accession Number: 20192607088761
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Record 302 of
Title:Curing shrinkage stress and deformation analysis of adhesive bonding large aperture mirror
Author(s):Sun, Li-Jun(1); Li, Li-Bo(1); Li, Si-Yuan(1); Zhao, Qiang(1); Sun, Jian(1); Wu, Jun-Qiang(1); Hu, Bing-Liang(1)
Source: Proceedings of SPIE - The International Society for Optical Engineering Volume: 10837 Issue: DOI: 10.1117/12.2505710 Published: 2019
Abstract:The influence of adhesive bonding and curing on the accuracy of mirror surface shape was analyzed to realize low-stress assembly of large aperture mirror. Firstly, based on Hooke's law, a curing shrinkage stress equation was deduced, taking deformation of the mirror and support structure into account under the boundary condition of continuous edge bond, and key parameters effecting mirror deformation were obtained. Secondly, for a 514mm ULE spectrometer primary mirror with an inserts structure mosaiced and bonded on mirror-back, an equivalent linear expansion coefficient method was used for finite element modeling. The shrinkage stress at the bond edge of mirror and the mirror surface shape were analyzed. It's found that adhesive shrinkage has a significant effect on the mirror surface shape. Finally, the inserts structure of mirror assembly was optimized. In contrast to the non-optimum structure, the average stress of adhesive surface caused by adhesive curing shrinkage reduced from 0.28MPa to 0.18MPa, and the mirror surface shape (Root Mean Square, RMS) reduced from 0.029λ to 0.017λ. Finite element analysis results of the mirror assembly were given at last, surface shape accuracy (RMS) of mirror is 0.012λ under a load case of 1g gravity, and the first-order natural frequency of the component is 216 Hz. The obtained results showed that a suitable optimized support structure can effectively relieve adhesive curing stress, and also satisfy the design requirements for both the static and dynamic stiffness. ? 2019 SPIE.
Accession Number: 20190506432459
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Record 303 of
Title:High energy closed-loop cycle narrow linewidth optically pumped XeF(C-A) blue laser at a repetition rate of 10 Hz
Author(s):Shen, Yanlong(1,2); Zhu, Feng(1); Yu, Li(3); Luan, Kunpeng(1); Tao, Mengmeng(1); Huang, Chao(1); Chen, Hongwei(1); Ma, Lianying(1); Zhao, Liu(1); An, Xiaoxia(1); Yi, Aiping(1); Li, Gaopeng(1)
Source: Optics Express Volume: 27 Issue: 3 DOI: 10.1364/OE.27.002258 Published: February 4, 2019
Abstract:We report for the first time on a closed-loop cycle narrow linewidth XeF(C-A) blue laser at a repetition rate of up to 10 Hz with each pulse energy of >1 J. A FWHM linewidth of less than 1.5 nm (minimum to 1.1 nm) with a highly stable wavelength centered at 488.3 nm was achieved by employing a polarization-independent custom-designed narrowband optical filter (NBOF) into the cavity. The pulse energy, as well as the repetition rate, to the best of our knowledge, is the highest ever reported in the narrow linewidth XeF(C-A) blue lasers at repetitively-pulsed mode. ? 2019 Optical Society of America
Accession Number: 20190606475242
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Record 304 of
Title:Road meteorological condition sensor based on multi-wavelength light detection
Author(s):Ruan, Chi(1); Wang, Yuntao(1); Ma, Xinxu(1); Kang, Heng(1)
Source: Proceedings of SPIE - The International Society for Optical Engineering Volume: 11052 Issue: DOI: 10.1117/12.2522311 Published: 2019
Abstract:Road surface meteorological conditions are very important for traffic safety. According to the statistics, the ratio of traffic accidents that occur on icy, wet and dry road surface is about 4.2:1.6:1. A remote road surface meteorological condition sensor based on multi-wavelength light was developed in this paper which could identify the road surface condition including dry, wet, icy and snow, that may be vital for preventing traffic accidents. By using multi-wavelength optical remote sensing technology and near infrared light source, the diffuse reflectance spectrum of road surface can be detected. The four road surface states of dry, wet, ice and snow can be measured with non-contact method, and the thickness of pavement water film can also be measured. Such road sensors were used on G50 highway in Chongqing, China. Experiment results show that the system could meet the requirements well. ? 2019 SPIE.
Accession Number: 20190806535061
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Record 305 of
Title:Muti-stage learning for gender and age prediction
Author(s):Fang, Jie(1,2); Yuan, Yuan(3); Lu, Xiaoqiang(1); Feng, Yachuang(1)
Source: Neurocomputing Volume: 334 Issue: DOI: 10.1016/j.neucom.2018.12.073 Published: 21 March 2019
Abstract:Automatic gender and age prediction has become relevant to an increasing amount of applications, particularly under the rise of social platforms and social media. However, the performances of existing methods on real-world images are still not satisfactory as we expected, especially when compared to that of face recognition. The reason is that, facial images for gender and age prediction have inherent small inter-class and big intra-class differences, i.e., two images with different skin colors and same age category label have big intra-class difference. However, most existing methods have not constructed discriminative representations for digging out these inherent characteristics very well. In this paper, a method based on muti-stage learning is proposed: The first stage is marking the object regions with an encoder-decoder based segmentation network. Specifically, the segmentation network can classify each pixel into two classes, "people" and others, and only the "people" regions are used for the subsequent processing. The second stage is precisely predicting the gender and age information with the proposed prediction network, which encodes global information, local region information and the interactions among different local regions into the final representation, and then finalizes the prediction. Additionally, we evaluate our method on three public and challenging datasets, and the experimental results verify the effectiveness of our proposed method. ? 2019 Elsevier B.V.
Accession Number: 20190306396646
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Record 306 of
Title:Design of SiC mirror subsystem of a space-based astronomy telescope
Author(s):Feng, Liang-Jie(1); Ding, Jiao-Teng(1); Zou, Gang-Yi(1)
Source: Proceedings of SPIE - The International Society for Optical Engineering Volume: 10837 Issue: DOI: 10.1117/12.2504931 Published: 2019
Abstract:A Φ450mm primary mirror subsystem of a space-based astronomy telescope was designed with mass, optical surface distortion and reflectivity requirement. The open-back primary mirror was made of pressure-less sintering silicon carbide, light-weighted at a ratio of approximately 70%. Three side supporting invar flexure bipods were designed to minimize the assembling stress and the thermal stress. The high reflection was obtained from the optical surface cementite. The mirror weighted 7kg and the reflectivity was 97% after optical polishing. The mirror subsystem was precisely assembled under the strict technical condition. The optical test with interferometer showed that the optical surface distortion is less than 1/40λ rms, which met the critical optical requirements for the primary mirror of the space-based astronomy telescope. ? 2019 SPIE.
Accession Number: 20190506432450
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Record 307 of
Title:Corner Detection-Based Segmentation Algorithm of Bioresorbable Vascular Scaffold Strut Contours
Author(s):Yao, Linlin(1,2); Jin, Qinhua(3); Jing, Jing(3); Chen, Yundai(3); Cao, Yihui(1); Li, Jianan(1); Zhu, Rui(1)
Source: Guangxue Xuebao/Acta Optica Sinica Volume: 39 Issue: 7 DOI: 10.3788/AOS201939.0715001 Published: July 10, 2019
Abstract:According to the prior knowledge about obvious quadrilateral feature of bioresorbable vascular scaffold (BVS) struts in an intravascular optical coherence tomography (IVOCT) image, this study proposes a novel algorithm based on four corners of BVS struts to automatically obtain their contours in the IVOCT imaging system. It solves the problem that dynamic programming (DP) algorithm, which is a contour-based algorithm, is not sufficiently accurate because of the influence of the fractures inside the struts and blood artifacts around the struts. Experimental results show that the proposed algorithm achieves an average Dice's coefficient of 0.88 for the strut segmentation areas, which is increased by approximately 0.08 compared to the result obtained by the DP algorithm. This algorithm can accurately and robustly segment BVS struts in the IVOCT image, and thus it can better assist doctors in the automatic strut malapposition analysis in clinical applications. ? 2019, Chinese Lasers Press. All right reserved.
Accession Number: 20193607400985
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Record 308 of
Title:Relationship between angle error and image rotation of Sagnac transverse shearing interferometer
Author(s):Chou, Xiao-Quan(1); Jiao, Qiao-Li(1); Sun, Jian(1); Ren, Wen-Zhen(1); Li, Xiao-Yan(1)
Source: Proceedings of SPIE - The International Society for Optical Engineering Volume: 11068 Issue: DOI: 10.1117/12.2523884 Published: 2019
Abstract:In order to solve the image rotation in Sagnac transverse shearing interferometer, a model system is built on ray vector tracing and rotation matrix theory, as well as the theoretical imaging orientation and the actual imaging orientation with the angle error are demonstrated. Besides, the relation between the angle error and the rotation of the image body is concluded, which provides a theoretical guidance for optical alignment in Sagnac transverse shearing interferometer. Finally, an optimized optical alignment scheme is provided by the discussion of the angle error in the assembly and system-level loading process, which is also validated by optical alignment instance. ? COPYRIGHT SPIE. Downloading of the abstract is permitted for personal use only.
Accession Number: 20192106969522
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Record 309 of
Title:Mechanism design of a low temperature resistant and high precision zoom lens
Author(s):Gao, Bo(1); Qiang, Zihao(1); Yang, Hongtao(1); Chen, Weining(1); Chang, Sansan(1); Zhang, Zhi(1); Fei, Jiaqi(1); Zhang, Yue(1); Zhang, Guangdong(1); Zhao, Yue(1); Fan, Erlei(1)
Source: Proceedings of SPIE - The International Society for Optical Engineering Volume: 10839 Issue: DOI: 10.1117/12.2507810 Published: 2019
Abstract:In the light of optical-electronic imaging system,designed a continuous zoom lens with a optical aperture of 60mm and a zoom range of 18-246mm. Summarized the disadvantages of the former zoom lens and a low temperature resistant and high precision structure,named the special-shaped slide and cam zoom structure is proposed, and carrying out the theoretical analysis and the detailed structural design. Theoretical analysis shows that this kind of structure can make the sliding friction between the cam and the main mirror tube turned into rolling friction,thus reducing the torque demand.it also helps to eliminate the stuck phenomenon of the cam in low temperature environment.The special-shaped slide frame structure can help eliminate the tilt Angle of the moving mirror group in the zoom process,thus reducing the variation of optic axis.In the he final test, the zoom time is not longer than 8s in the environment which temperature is only-45°Ci1/4and the variation of optic axis is smaller than 0.3milliradian,both meet the target requirement. ? 2019 SPIE.
Accession Number: 20190706489067
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Record 310 of
Title:High reflecting film deposition of all-CFRP mirror
Author(s):Wang, Yongjie(1); Wu, Xiaoge(1); Li, Haochuan(1); Xu, Liang(1); Ding, Jiaoteng(1); Xie, Yongjie(1); Ma, Zhen(1)
Source: Proceedings of SPIE - The International Society for Optical Engineering Volume: 10837 Issue: DOI: 10.1117/12.2504867 Published: 2019
Abstract:To improve the reflecting properties of all CFRP mirror, a high reflecting coating must be prepared on the mirror surface. In this paper, the effect of the roughness, film material and the deposition temperature on the reflecting rate was discussed. In the experiments, it was observed that the film exhibited higher reflecting rate on the smoother surface; meanwhile, the deposition rate must be controlled below the soften point of the surface replicated resin; if not, pits will generate on the surface and reduce reflecting rate. Ag film system exhibited higher reflecting rate than Al films. Finally, a multilayer film Ag and SiO2 was deposited on CFRP mirror, with a reflecting rate over 95% between 450nm and 800 nm. ? 2019 SPIE.
Accession Number: 20190506432473
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Record 311 of
Title:Precision of the attitude algorithm of the strap-down inertial navigation system
Author(s):Zhang, Wei(1); Shi, Kui(1); Ai, Yun(1); Guo, Juan(1)
Source: Proceedings of SPIE - The International Society for Optical Engineering Volume: 10839 Issue: DOI: 10.1117/12.2504808 Published: 2019
Abstract:Based on the principle of the strap-down inertial navigation system and the attitude algorithm, a novel evaluation method is proposed. It could be used to effectively diagnostic the precision of the attitude algorithm. The experimental data including Algorithm 1 (N=2, P=0, optimal two-sample), Algorithm 2 (N=2, P=1) and Algorithm 3 (N=2, P=2) is recorded. The precision of the three algorithms is evaluated by calculating the relative error. In addition, the influence of the sampling frequency on the precision is investigated. The test results show that the precision of Algorithm 2 and Algorithm 3 is approximate; as the sampling frequency is improved from 1Hz to 20Hz, the precision of the attitude algorithm can research 0.08°. When choosing the attitude algorithm of the strap-down inertial navigation system, increasing the number of the sample not always depresses the coning error, improving the sampling frequency and using the former attitude to renew the number of the sample of the period could improve the precision of the attitude algorithm, further. ? 2019 SPIE.
Accession Number: 20190706488938
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Record 312 of
Title:Opto-mechanical integrated simulation technology of trussed front structure for space solar telescope
Author(s):Xu, Guangzhou(1); Ruan, Ping(1); Yang, Jianfeng(1)
Source: Proceedings of SPIE - The International Society for Optical Engineering Volume: 11341 Issue: DOI: 10.1117/12.2540160 Published: 2019
Abstract:The trussed front structure is the important assembly for space solar telescope; compared to the other assemblies on the solar telescope, it can be easily affected by the solar heat flux. Evaluating the influence of optical performance change of trussed front structure for space solar telescope under the external loads is a key technical problem that should be taken care. Opto-mechanical integrated simulation technology as the important method to evaluate the optical performance change under the external loads, it is selected and researched to evaluate change of optical performance for solar space telescope. First, opto-mechanical simulation algorithm is studied and the interface program ISIA is developed based on the research of the algorithm. Second, the correctness validation of ISIA is validated and the validation result demonstrates that the calculation precision of ISIA is higher and to be equivalent to the Sigfit. The ISIA provides the high-precision algorithm and tool support to realize the opto-mechanical integrated analysis of space solar telescope. Third, the optical performance evaluation of space solar telescope under the certain thermal control case is carried out. Based on the opto-mechanical simulation result, the data reference is provided for the structural design of trussed front structure for the space solar telescope. Besides, the environmental adaption design is improved as well for the space solar telescope. ? 2019 SPIE.
Accession Number: 20200408063324
