2019
2019
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Record 349 of
Title:Optimal Design of Cam Curve Structure of the 30× Continuous Zoom System
Author(s):Peng, Jian-Wei(1); Shi, Kui(1); Lei, Yang-Jie(1); Mei, Chao(1); Wu, Li(1)Source: Guangzi Xuebao/Acta Photonica Sinica Volume: 48 Issue: 12 DOI: 10.3788/gzxb20194812.1222002 Published: December 1, 2019Abstract:Taking a 30× continuous zoom lens as an example, the method of changing the pressure angle of the curve is researched. The pressure angle is taken as the objective function, and the cam curve rotation angle is constructed as a piecewise function to re-divide the angle, the position where the pressure angle is too large is distributed large rotation angle, and the rotation angle of position where the pressure angle is small is compressed, so as to reduce the overall pressure of the curve, and also to restrain the large inflection point effectively in the curve. The optimization results of various angular allocation values are compared with the simulation using Matlab and the optimal cam curve is obtained. The optimal result reduces the maximum pressure angle of the curve from the original 76.9° to 41.9°. The experimental results show that the zoom lens optimized by this method has good imaging quality, the line-of-sight liner is not more than 3 pixels, and the stability of the line-of-sight is not more than 1 pixel. ? 2019, Science Press. All right reserved.Accession Number: 20200708160502 -
Record 350 of
Title:Excessively tilted fiber grating based Fe3O4 saturable absorber for passively mode-locked fiber laser
Author(s):Wang, Hushan(1,2,3); Zhao, Fengyan(1,2,3); Yan, Zhijun(1,4); Hu, Xiaohong(1); Zhou, Kaiming(1,5); Zhang, Ting(1,2); Zhang, Wei(1); Wang, Yishan(1,3); Zhao, Wei(1,3); Zhang, Lin(5); Sun, Chuandong(1)Source: Optics Express Volume: 27 Issue: 11 DOI: 10.1364/OE.27.015693 Published: 2019Abstract:A novel approach to saturable absorber (SA) formation is presented by taking advantage of the mode coupling property of excessively tilted fiber grating (Ex-TFG). Stable mode-locked operation can be conveniently achieved based on the interaction between Ex- TFG coupled light and deposited ferroferric-oxide (Fe3O4) nanoparticles. The central wavelength, bandwidth and single pulse duration of the output are 1595 nm, 4.05 nm, and 912 fs, respectively. The fiber laser exhibits good long-term stability with signal-to-noise ratio (SNR) of 67 dB. For the first time, to the best of our knowledge, Ex-TFG based Fe3O4 SA for mode-locked fiber laser is demonstrated. ? 2019 Optical Society of America.Accession Number: 20192307001976 -
Record 351 of
Title:Compact, robust, and repetition-rate-locked all-polarization-maintaining femtosecond fiber laser system
Author(s):Cai, Yajun(1,2,3); Pan, Ran(1); Zhang, Tong(4); Liu, Yuanshan(1); Wang, Hushan(1); Zhang, Wei(1); Wang, Yishan(1); Zhao, Wei(1,3); Feng, Ye(1,3); Hu, Xiaohong(1,3)Source: Optical Engineering Volume: 58 Issue: 4 DOI: 10.1117/1.OE.58.4.046108 Published: April 1, 2019Abstract:We demonstrate a 200-MHz all polarization-maintaining, repetition-rate-locked femtosecond fiber laser system with a total electrical power consumption of 11 W. The center wavelength, spectral width, pulse width, and average output power of the laser are 1558.8 nm, 34 nm, 139 fs, and 77.6 mW, respectively. The proposed laser system that integrates all optical components and locking electronics has a volume less than 1.5 L, a mass of 1.3 kg, and a fast locking time of 3 s (from the free running state to the repetition-rate-locked state). Using a hydrogen maser as the frequency reference, after locking, the Allan deviation is 2.8 mHz at a gate time of 1 s. Further, we place the repetition-rate-locked fiber laser system on a homemade shaker table with peak and rms accelerations of 1.97 and 0.7 g, respectively; the experimental results show that the locking state can be maintained robustly with Allan deviation of 2.0 mHz. The highly integrated, robust fiber laser system has potential applications in the areas of ultralow-noise microwave generation and high-precision distance measurement in outdoor environments. ? 2019 Society of Photo-Optical Instrumentation Engineers (SPIE).Accession Number: 20192006915874 -
Record 352 of
Title:Electronic structure and optical properties of La-doped KSr2Nb5O15: A first-principles investigation
Author(s):Chen, Qian(1); Gao, Feng(1); Xu, Jie(1); Cao, Shuyao(1); Guo, Yiting(1); Cheng, Guanghua(2)Source: Ceramics International Volume: 45 Issue: 8 DOI: 10.1016/j.ceramint.2019.02.040 Published: 1 June 2019Abstract:The electronic structure and the anisotropic optical properties of lanthanum doped in KSr2Nb5O15 (KSN-La) were investigated by the first principles calculation dependent on the density functional theory, which was then supported by experiments. With La3+ doping in the KSN lattice, the band gap of KSN-La becomes smaller and the lattice structure transforms from tetragonal to orthorhombic due to the imbalance of charge of the KSN structure affected by the La3+ doping. The analysis of the anisotropic optical properties showed that the value of optical dielectric constant along [001] direction was larger compared to [010] and [100]. The calculated dielectric properties were in good accordance to the experimental results. KSN-La presented a larger dielectric constant, provided that La3+ was able to compensate the vacancies of the A sites of KSN, which were generated during the sintering process, leading to an effective enhancement of the dielectric constant. ? 2019 Elsevier Ltd and Techna Group S.r.l.Accession Number: 20190706504126 -
Record 353 of
Title:Experimental demonstration of quasi-omni-directional transmitter for underwater wireless optical communication based on blue LED array and freeform lens
Author(s):Han, Biao(1,2); Zhao, Wei(1); Zheng, Yunqiang(1); Meng, Jiacheng(1); Wang, Tao(1,2); Han, Yi(1); Wang, Wei(1,3); Su, Yulong(1); Duan, Tao(1); Xie, Xiaoping(1)Source: Optics Communications Volume: 434 Issue: DOI: 10.1016/j.optcom.2018.10.037 Published: 1 March 2019Abstract:In this paper, we propose a transmitter with 150odivergence angle and more than 90% uniformity of radiation intensity for quasi-omni-directional underwater wireless optical communication (UWOC) by applying freeform lens into LED array. We demonstrate its performance under different transmitting directions with 19Mbps data rate and 8m communication distance in an experimental tank whose volume is 20m×20m×14m and attenuation coefficient is about 0.40m?1. The result shows that the variation of bit error rate (BER) is about three orders of magnitude with the help of freeform lens when direction deviation angle is between -75oand +75o, which is reduced five orders compared with the situation without the lens. The presented result is useful to make it easier to establish communication link and improve the performance of UWOC system when transmitter direction shake exists. Also, it implies that we could apply different freeform lenses into LED array to reshape transmitting illumination according to different demands for UWOC application. ? 2018 Elsevier B.V.Accession Number: 20184606082166 -
Record 354 of
Title:Facial Attention based Convolutional Neural Network for 2D+3D Facial Expression Recognition
Author(s):Jiao, Yang(1); Niu, Yi(1,2); Zhang, Yuting(1); Li, Fu(1); Zou, Chunbo(3); Shi, Guangming(1)Source: 2019 IEEE International Conference on Visual Communications and Image Processing, VCIP 2019 Volume: Issue: DOI: 10.1109/VCIP47243.2019.8965843 Published: December 2019Abstract:Discriminative facial parts are essential for facial expression recognition (FER) tasks because of small inter-class differences and large intra-class variations in expression images. Existing methods localize discriminative regions with the aid of extra facial landmarks, such as action units (AU). However, it consumes a lot of manpower in manually labeling. To address this problem, in this paper, we propose an advanced facial attention based convolutional neural network (FA-CNN) for 2D+3D FER. The main contribution of FA-CNN is the facial attention mechanism, which enables the network to localize the discriminative regions automatically from multi-modality expression images without dense landmark annotations. Experimental results conducted on BU-3DFE demonstrate that FA-CNN achieves state-of-The-Art performance comparing with the existing 2D+3D FER techniques, and the discriminative facial parts estimated by the facial attention mechanism are highly interpretable and consistent with human perception. ? 2019 IEEE.Accession Number: 20200708164528 -
Record 355 of
Title:Atomic-Scale Simulation of the Contact Behavior and Mechanism of the SWNT-AgNW Heterostructure
Author(s):Cui, Jianlei(1,2,3,4); Zhang, Jianwei(1,2); Wang, Xuewen(1,3,5); Theogene, Barayavuga(1); Wang, Wenjun(1); Tohmyoh, Hironori(4); He, Xiaoqiao(5); Mei, Xuesong(1)Source: Journal of Physical Chemistry C Volume: 123 Issue: 32 DOI: 10.1021/acs.jpcc.9b05181 Published: August 15, 2019Abstract:We investigated the interfacial contact behavior of the side-to-side biaxial heterostructure between carbon nanotubes and silver nanowires on an atomic scale. The nanotubes can move along the nanowire periphery and keep pace with the silver nanowires, and in some cases, a collapse occurs and quickly creates a domino effect that readily forms the bilayer graphene-like structures with a face-to-face π-πstacking effect that adhere firmly to the nanowire surface. When the diameter of an armchair nanotube is very large, the bilayer graphene-like structure that has been formed can scroll onto the nanowire periphery and wrap around the nanowire to form a core/shell hybrid structure that will eventually be transformed into a double-walled carbon nanotube structure. In other circumstances that are affected by factors such as temperature and the nanotube structure, the carbon nanotube does not easily collapse; instead, it retains its intrinsic circular form. The mechanism for interfacial contact behavior reveals that the van der Waals interactions play an important role in the entire process. The effects of the interfacial contact behavior and the final atomic configuration may provide valuable theoretical guidance for designing and fabricating hybrid structures with broad potential applications, such as nanoelectronic devices and functional composite materials. Copyright ? 2019 American Chemical Society.Accession Number: 20193607402012 -
Record 356 of
Title:Random scattering of images and visibility enhancement via stochastic resonance
Author(s):Zhang, Yongbin(1,2); Liu, Hongjun(1,3); Huang, Nan(1); Wang, Zhaolu(1)Source: Optical Engineering Volume: 58 Issue: 4 DOI: 10.1117/1.OE.58.4.046105 Published: April 1, 2019Abstract:We investigate numerically the random scattering of two-dimensional (2-D) images and the visibility enhancement via stochastic resonance both in intensity and momentum spaces. The multiple scattering destroys the direct transmission of photons, but some ballistic photons carrying the image information still penetrate the scattering media. The underlying ballistic image signals exhibit an instability and are enhanced at the expense of scattering noise under self-focusing nonlinearity, which is described as a stochastic resonance. It is found that the higher ratio of ballistic signals to scattering noise triggers a stronger instability. The effect of visibility enhancement in different scattering conditions is discussed, and the 2-D quasiparticle motion model is designed to analyze the nonlinear dynamic evolution. Our results provide potential guidance for noisy image detection. ? 2019 Society of Photo-Optical Instrumentation Engineers (SPIE).Accession Number: 20192006916926 -
Record 357 of
Title:Preparation and Characteristics of SiO2/VO2 Double-Layer Thermochromic Coatings for Smart Window
Author(s):Liu, Peng(1); Liang, Liping(1); Xu, Yao(2)Source: Guangxue Xuebao/Acta Optica Sinica Volume: 39 Issue: 4 DOI: 10.3788/AOS201939.0416001 Published: April 10, 2019Abstract:SiO2/VO2 thermochromic coatings are prepared via VO2 sintering alone and SiO2/VO2 co-sintering, respectively. The microstructure, thermochromic properties and optical properties of samples are studied. The experimental results show that both the microstructure and the above properties of the coatings are strongly dependent on the deposition process, whereas the type of SiO2 precursor sols only have little effect on the microstructure and even less effect on the thermochromic and optical properties. When the coatings are prepared by the VO2 alone-sintering routine, the SiO2/VO2 coatings obtain high transmittance under the condition of slight loss in thermochromic properties. The double-layer coating sample exhibited good comprehensive performance, its near infrared switching rate at 2000 nm value is 39.6%, the solar energy modulation value is 8.4%, and the integral visible transmittance and the integral solar transmittance at 25℃ are 68.4% and 72.0%, respectively. ? 2019, Chinese Lasers Press. All right reserved.Accession Number: 20192006931122 -
Record 358 of
Title:Preparation and thermal optimization of the proton-implanted high-gain Nd3+-doped laser glass waveguide
Author(s):Chen, Jing-Yi(1); Wang, Yi(1); Wang, Zhi-Ming(1); Zhang, Liao-Lin(2); Guo, Hai-Tao(3); Liu, Chun-Xiao(1)Source: Japanese Journal of Applied Physics Volume: 58 Issue: 3 DOI: 10.7567/1347-4065/aafb49 Published: March 1, 2019Abstract:In this work, the high-gain Nd3+-doped laser glass was chosen as the target material, and the optical waveguide was formed on the glass by the H+ ion implantation under the conditions of a 8.0 ×1016-ions cm-2 fluence and a 0.4 MeV energy. The post-annealing at 200 °C for 1 h was applied to improve the optical quality of the waveguide. A metallographic microscope was used to detect changes in morphology caused by implanted ions in the high-gain Nd3+-doped laser glass. The characteristics of the ion-implanted high-gain Nd3+-doped laser glass optical waveguide, such as the dark-mode profiles and the near-field intensity distributions, were measured by experimental instruments including a prism coupler and an end-coupling system. The effects of nuclear energy loss of implanted ions on the refractive index variation of the substrate were analyzed by the reflectivity calculation method. The interaction mechanism of implanted protons with the high-gain Nd3+-doped laser glass was discussed by the SRIM 2013 code. It lays a theoretical and experimental basis for the development of high-gain Nd3+-doped glass waveguide lasers and amplifiers. ? 2019 The Japan Society of Applied Physics.Accession Number: 20191306688302 -
Record 359 of
Title:Design and Experiment of Vibration Reduction Scheme for Sensitive Detectors Based on Random Vibration
Author(s):Yue, Kaiqin(1); Wang, Feicheng(1); Zhang, Hongjian(1); Li, Siyuan(1)Source: IOP Conference Series: Materials Science and Engineering Volume: 688 Issue: 3 DOI: 10.1088/1757-899X/688/3/033085 Published: December 6, 2019Abstract:This work proposes a vibration damping scheme using a metal rubber damper for space camera mechanically sensitive detectors. The feasibility of the scheme is verified by the analysis of the principle of metal rubber damper. According to the relevant test conditions, the relevant parameters of the metal rubber damper are designed, and the vibration damping effect of the scheme is verified by experiments. The research results show that the use of metal rubber damper can play a role in the vibration energy transfer of the space camera, thus effectively reducing the RMS value of the acceleration in the main vibration direction. ? Published under licence by IOP Publishing Ltd.Accession Number: 20202008646744 -
Record 360 of
Title:Scratch hardness of rare-earth substituted calcium aluminosilicate glasses
Author(s):She, Jiangbo(1,2); Sawamura, Shigeki(1,3); Wondraczek, Lothar(1)Source: Journal of Non-Crystalline Solids: X Volume: 1 Issue: DOI: 10.1016/j.nocx.2019.100010 Published: March 2019Abstract:We report lateral deformation experiments on rare earth substituted glasses from percalcic CaO-Al2O3-SiO2-Tm2O3. Using instrumented Berkovich indentation with normal loads below 100 mN, the scratch hardness was obtained from the work of lateral deformation per deformed volume in the elastic-plastic regime. The positive effect of rare-earth substitution on normal hardness, Poisson's ratio and Young's modulus was found to extent also to scratch hardness: in 25CaO-15Al2O3-60SiO2, partial replacement of alumina by Tm2O3 leads to an enhancement of the scratch hardness by about 1 GPa per 2 mol% of substitution, reaching the highest values of scratch hardness which have been reported for oxide glasses thus far. The enhancement of scratch hardness is attributed to enhanced cation packing fraction and super-structural cohesion as a result of rare earth substitution. The previously reported linear correlation between scratch hardness and bulk modulus is confirmed. ? 2019 The AuthorsAccession Number: 20191006599969