2014
2014
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Record 409 of
Title:Effects of stitching pattern on diffractive telescope image quality
Author(s):Zhang, ZhouFeng(1); Xie, YongJun(1); Kang, FuZeng(1); Wang, YanJun(1)Source: Proceedings of SPIE - The International Society for Optical Engineering Volume: 9142 Issue: DOI: 10.1117/12.2054364 Published: 2014Abstract:Diffraction image technology is an updated technology. It has more potential for developing the larger aperture and lightweight telescope than the conventional refractive and reflective optics. In order to develop a large aperture diffractive telescope, the key is to solve the problem of large aperture lens stitching. Different stitching patterns have different effects on the image quality. However, the stitching pattern for diffractive telescope is different from the conventional refractive and reflective telescope. This paper, for the first time, studies the theory of stitching pattern for diffractive telescope. On the basis of theoretical analysis, a long-wavelength infrared diffractive telescope of segmented-lens is designed and for the first time, good results through stitching experiments have been achieved. According to theoretical analysis and experiment verification, the paper gives the best stitching pattern on diffractive telescope. ? 2014 Copyright SPIE.Accession Number: 20141217474345 -
Record 410 of
Title:Generation of bidirectional stretched pulses in a nanotube-mode-locked fiber laser
Author(s):Yao, Xiankun(1)Source: Applied Optics Volume: 53 Issue: 1 DOI: 10.1364/AO.53.000027 Published: January 1, 2014Abstract:The bidirectional stretched pulses in a nanotube-based erbium-doped fiber laser are observed experimentally for the first time to our best knowledge. The proposed fiber laser generates two stable pulse trains in opposite directions with different central wavelengths, pulse widths, and repetition rates. In addition, the bidirectional operations with the same central wavelengths are also demonstrated by changing the polarization controller and pump power. Experimental results suggest that the cavity asymmetries together with the fiber birefringence play key roles in the formation of these unique features. ? 2014 Optical Society of America.Accession Number: 20140217184120 -
Record 411 of
Title:Phase retrieval without unwrapping by single-shot dual-wavelength digital holography
Author(s):Min, Junwei(1); Yao, Baoli(1); Zhou, Meiling(1); Guo, Rongli(1); Lei, Ming(1); Yang, Yanlong(1); Dan, Dan(1); Yan, Shaohui(1); Peng, Tong(1)Source: Journal of Optics (United Kingdom) Volume: 16 Issue: 12 DOI: 10.1088/2040-8978/16/12/125409 Published: December 1, 2014Abstract:A phase retrieval method by using single-shot dual-wavelength digital holography is proposed. Each single wavelength hologram is extracted from the color CCD recorded hologram at one exposure, and the unwrapped phase image of object can be reconstructed directly. Different from the traditional multiple wavelength phase unwrapping techniques, any single complex wavefronts at different wavelengths have no need to be calculated any more. Thus, the phase retrieval is computationally fast and straightforward, and the limitations on the total optical path difference are significantly relaxed. The practicability of the proposed method is demonstrated by both simulated and experimental results. ? 2014 IOP Publishing Ltd.Accession Number: 20144900296617 -
Record 412 of
Title:Investigation on the factors to influence terahertz absorption spectrum
Author(s):Fan, Wen-Hui(1)Source: International Symposium on Ultrafast Phenomena and Terahertz Waves, ISUPTW 2014 Volume: Issue: DOI: 10.1364/isuptw.2014.tus6_3 Published: October 13, 2014Abstract:nullAccession Number: 20151900832470 -
Record 413 of
Title:Controllable synthesis of monodisperse CaF2 microsphere and the investigation on luminous performance of CaF2:Ce3+/Tb 3+
Author(s):Sun, X.(1); Hu, X.(1,2); Fan, J.(3); Zhan, S.(1); Wang, Y.(1); Wang, Z.(1); Sun, Q.(1); Hao, Y.(1)Source: Technical Proceedings of the 2014 NSTI Nanotechnology Conference and Expo, NSTI-Nanotech 2014 Volume: 1 Issue: DOI: Published: 2014Abstract:In this paper, highly uniform and well-dispersed CaF2 microsphere with tunable particles size have been successfully synthesized by a facile hydrothermal process using ethylenediaminetetraacetic acid disodium as a complexing reagent. The XRD results indicated that the as-prepared microspheres were of cubic phases and had good crystallinity and purity. The TEM and SEM results reveal that monodisperse and uniform hollow sphere with rough surfaces can be prepared by this approach. In addition, Ce3+/Tb 3+-codoped CaF2 sphere can be prepared similarly. Excitation and emission spectra are shown that the samples can absorb ultraviolet light and emit light at 335 nm. In the emission spectrum, it is clear that emission intensity of Ce3+ decreases with increasing Tb3+, it shows that efficient energy transfer from Ce3+ to Tb3+ may occur. It significantly improves the absorption range and intensity of the samples. That is extremely useful and has potential application value in display, light, laser, optical information transfer, scintillator and optoelectronic devices.Accession Number: 20143918183434 -
Record 414 of
Title:Tag-Saliency: Combining bottom-up and top-down information for saliency detection
Author(s):Zhu, Guokang(1,2); Wang, Qi(1); Yuan, Yuan(1)Source: Computer Vision and Image Understanding Volume: 118 Issue: DOI: 10.1016/j.cviu.2013.07.011 Published: January 2014Abstract:In the real world, people often have a habit tending to pay more attention to some things usually noteworthy, while ignore others. This phenomenon is associated with the top-down attention. Modeling this kind of attention has recently raised many interests in computer vision due to a wide range of practical applications. Majority of the existing models are based on eye-tracking or object detection. However, these methods may not apply to practical situations, because the eye movement data cannot be always recorded or there may be inscrutable objects to be handled in large-scale data sets. This paper proposes a Tag-Saliency model based on hierarchical image over-segmentation and auto-tagging, which can efficiently extract semantic information from large scale visual media data. Experimental results on a very challenging data set show that, the proposed Tag-Saliency model has the ability to locate the truly salient regions in a greater probability than other competitors. ? 2013 Elsevier Inc. All rights reserved.Accession Number: 20135217125410 -
Record 415 of
Title:Cavity linewidth narrowing by tunneling induced double dark resonances in triple quantum dot molecules
Author(s):Tian, Si-Cong(1); Wan, Ren-Gang(2); Li, Lian-He(1); Tong, Cun-Zhu(1); Ning, Yong-Qiang(1)Source: Optics Communications Volume: 334 Issue: DOI: 10.1016/j.optcom.2014.08.011 Published: January 15, 2015Abstract:A scheme for obtaining a tunable ultranarrow cavity transmission controlled by two tunneling in triple quantum dots system is proposed. In such system, the tunneling can induce double dark resonances, resulting in the appearance of two transparency windows. With the steep dispersion within the narrowed transparency windows, an ultranarrow transmission peak can be obtained, compared with that of double quantum dots system. Furthermore, by varying the energy splitting, the linewidth and the position of the ultranarrow transmission peak can be engineered. Because no coupling laser is required, the scheme proposed here is more convenient for future experiments and applications in optics, and may be useful in designing novel optoelectronic devices. ? 2014 Elsevier B.V.Accession Number: 20144200107391 -
Record 416 of
Title:Part-based online tracking with geometry constraint and attention selection
Author(s):Fang, Jianwu(1); Wang, Qi(2); Yuan, Yuan(1)Source: IEEE Transactions on Circuits and Systems for Video Technology Volume: 24 Issue: 5 DOI: 10.1109/TCSVT.2013.2283646 Published: May 2014Abstract:Visual tracking in condition of occlusion, appearance or illumination change has been a challenging task over decades. Recently, some online trackers, based on the detection by classification framework, have achieved good performance. However, problems are still embodied in at least one of the three aspects: 1) tracking the target with a single region has poor adaptability for occlusion, appearance or illumination change; 2) lack of sample weight estimation, which may cause overfitting issue; and 3) inadequate motion model to prevent target from drifting. For tackling the above problems, this paper presents the contributions as follows: 1) a novel part-based structure is utilized in the online AdaBoost tracking; 2) attentional sample weighting and selection is tackled by introducing a weight relaxation factor, instead of treating the samples equally as traditional trackers do; and 3) a two-stage motion model, multiple parts constraint, is proposed and incorporated into the part-based structure to ensure a stable tracking. The effectiveness and efficiency of the proposed tracker is validated upon several complex video sequences, compared with seven popular online trackers. The experimental results show that the proposed tracker can achieve increased accuracy with comparable computational cost. ? 2013 IEEE.Accession Number: 20142117748355 -
Record 417 of
Title:Design and evaluation of a pre-traveling wave deflector magnetic solenoid lens focused streak image tube
Author(s):Liu, Rong(1,2,3); Tian, Jin-Shou(1); Li, Hao(1,2); Wang, Qiang-Qiang(1,2); Wang, Chao(1); Wen, Wen-Long(1); Lu, Yu(1); Liu, Hu-Lin(1); Cao, Xi-Bin(1); Wang, Jun-Feng(1); Xu, Xiang-Yan(1); Wang, Xing(1)Source: Wuli Xuebao/Acta Physica Sinica Volume: 63 Issue: 5 DOI: 10.7498/aps.63.058501 Published: March 5, 2014Abstract:Owing to the excellent feature of ultrahigh temporal resolution, the streak image tube has been the indispensable scientific instrument for the application to measurement of ultrafast phenomena on subpicosecond time scale. In this paper, a new femtosecond streak image tube with both high temporal and spatial resolution is designed. To improve its integrated performance, a pair of traveling wave deflectors is located before a magnetic solenoid lens in the tube, which minimizes the electron transit time from anode to deflection plates and therefore reduces time dispersion and space charge effects. Using CST microwave studio finite element method, bandwidth and deflection sensitivity of traveling wave deflector have been studied numerically. The result shows that the wide bandwidth of the traveling wave deflectors designed is beneficial to slow down the electrical deflecting pulse to match the beam velocity in a wide frequency range, which can improve the deflection sensitivity. After tracing the trajectory of electrons and calculating the modulation transform function, we get temporal resolution of 220 fs and spatial resolution above 100 lp/mm. Based on the aberration theory, the aberration formulas of electron trajectory are deduced, which systematically evaluate the imaging quality of streak image tube with modulation transfer function. Finally, static experiment is carried out, and the result shows that the static spatial resolution is better than 35 lp/mm. ? 2014 Chinese Physical Society.Accession Number: 20141217481652 -
Record 418 of
Title:Broadband high birefringence and low dispersion terahertz photonic crystal fiber
Author(s):Li, Shaopeng(1); Liu, Hongjun(1); Huang, Nan(1); Sun, Qibing(1)Source: Journal of Optics (United Kingdom) Volume: 16 Issue: 10 DOI: 10.1088/2040-8978/16/10/105102 Published: October 1, 2014Abstract:We propose a novel type of triangular lattice terahertz photonic crystal fiber with high birefringence and low dispersion in a wide spectrum range. The proposed structures have circular and elliptical air holes in the cladding. Properties of birefringence, confinement loss, and group velocity dispersion have been studied by using full-vector finite-element methods. Through adjusting the structural parameters of the photonic crystal fiber, birefringence up to 10-3 could be achieved in the frequency range of 0.1-5 THz. Moreover, group velocity dispersion curve in this frequency range is flat and the values are nearly zero. Therefore, it can be used to transmit broadband THz pulses with the polarization maintained. ? 2014 IOP Publishing Ltd.Accession Number: 20144200101708 -
Record 419 of
Title:The pulsed all fiber laser application in the high-resolution 3D imaging LIDAR system
Author(s):Gao, Cunxiao(1); Zhu, Shaolan(1); Niu, Linquan(1); Feng, Li(1); He, Haodong(1); Cao, Zongying(1)Source: Proceedings of SPIE - The International Society for Optical Engineering Volume: 9135 Issue: DOI: 10.1117/12.2048275 Published: 2014Abstract:An all fiber laser with master-oscillator-power-amplifier (MOPA) configuration at 1064nm/1550nm for the high-resolution three-dimensional (3D) imaging light detection and ranging (LIDAR) system was reported. The pulsewidth and the repetition frequency could be arbitrarily tuned 1ns～10ns and 10KHz～1MHz, and the peak power exceeded 100kW could be obtained with the laser. Using this all fiber laser in the high-resolution 3D imaging LIDAR system, the image resolution of 1024×1024 and the distance precision of ±1.5 cm was obtained at the imaging distance of 1km. ? 2014 SPIE.Accession Number: 20142617853501 -
Record 420 of
Title:High-efficiency terahertz-wave generation in silicon waveguides
Author(s):Liu, Hongjun(1); Li, Shaopeng(1); Wang, Zhaolu(1); Huang, Nan(1); Sun, Qibing(1)Source: Advanced Solid State Lasers, ASSL 2014 Volume: Issue: DOI: 10.1364/assl.2014.atu2a.24 Published: November 16, 2014Abstract:Terahertz (THz) wave generation via four-wave mixing (FWM) in silicon waveguides are investigated with mid-infrared pump. The maximum conversion efficiency of 1.37 % is realized when the pump peak power of 2000 W. ? OSA 2014.Accession Number: 20152000841123