2014
2014
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Record 181 of
Title:Sub-100 ns passively Q-switched Nd:LuAG laser with multi-walled carbon nanotube
Author(s):Chen, X.T.(1); Zhao, S.Z.(1); Zhao, J.(1); Yang, K.J.(1); Li, G.Q.(1); Li, D.C.(1); Qiao, W.C.(1); Li, T.(1); Zhang, H.J.(1); Feng, T.L.(1); Xu, X.D.(2); Zheng, L.H.(2); Xu, J.(2); Wang, Y.G.(3); Wang, Y.S.(3)Source: Optics and Laser Technology Volume: 64 Issue: DOI: 10.1016/j.optlastec.2014.04.019 Published: December 2014Abstract:We report the first demonstration of a diode-pumped passively Q-switched Nd:LuAG laser with a multi-walled carbon nanotube (MWCNT) as saturable absorber. A maximum average output power of 844 mW and pulses as short as 78 ns under a repetition rate of about 100 kHz were generated. A MWCNT Q-switched Nd:YAG laser was comparatively investigated, in comparison with which the Nd:LuAG laser showed lower threshold absorbed pump power and higher pulse energy, indicating a better energy storage ability of Nd:LuAG crystal than Nd:YAG. ? 2014 Elsevier Ltd.Accession Number: 20142117736658 -
Record 182 of
Title:Optimized graph-based segmentation for ultrasound images
Author(s):Huang, Qinghua(1); Bai, Xiao(2); Li, Yingguang(1); Jin, Lianwen(1); Li, Xuelong(3)Source: Neurocomputing Volume: 129 Issue: DOI: 10.1016/j.neucom.2013.09.038 Published: April 10, 2014Abstract:Segmentation of medical images is an inevitable image processing step for computer-aided diagnosis. Due to complex acoustic inferences and artifacts, accurate extraction of breast lesions in ultrasound images remains a challenge. Although there have been many segmentation techniques proposed, the performance often varies with different image data, leading to poor adaptability in real applications. Intelligent computing techniques for adaptively learning the boundaries of image objects are preferred. This paper focuses on optimization of a previously documented method called robust graph-based (RGB) segmentation algorithm to extract breast tumors in ultrasound images more adaptively and accurately. A novel technique named as parameter-automatically optimized robust graph-based (PAORGB) image segmentation method is accordingly proposed and performed on breast ultrasound images. A particle swarm optimization algorithm is incorporated with the RGB method to achieve optimal or approximately optimal parameters. Experimental results have shown that the proposed technique can more accurately segment lesions from ultrasound images compared to the RGB and two conventional region-based methods. ? 2013 Elsevier B.V.Accession Number: 20140717320589 -
Record 183 of
Title:Oxygen-implanted optical planar waveguides in Er3+/Yb 3+ -codoped silicate glasses for integrated laser generation
Author(s):Liu, Chun-Xiao(1,2); Xu, Jun(3); Xu, Xiao-Li(1); Wu, Shu(1); Wei, Wei(2,4); Guo, Hai-Tao(2); Li, Wei-Nan(2); Peng, Bo(2,4)Source: Optical Engineering Volume: 53 Issue: 3 DOI: 10.1117/1.OE.53.3.037101 Published: March 2014Abstract:Er3+/Yb3+-codoped silicate glasses are good candidates for the application of laser actions and signal amplification. Optical planar waveguides in Er3+/Yb3+-codoped silicate glasses are fabricated by 6.0-MeV oxygen-ion implantation with a dose of 6.0 × 1014 ions/cm2 at room temperature. The SRIM 2010 code is carried out to simulate the energy losses during the implantation process in order to obtain a better understanding of the waveguide formation. The guiding modes and near-field intensity distributions of the waveguide are characterized by the prism-coupling and end-face coupling methods. The refractive index profile and light propagation mode of the planar waveguide are numerically calculated by the reflectivity calculation method and finite difference beam propagation method. The waveguide has "well + barrier" refractive index distribution and its optical loss is ~1.02 dB/cm. The microluminescence and absorption investigation reveal that fluorescent and transmission properties in the waveguide are well preserved with respect to the bulk, suggesting promising potential for waveguide amplifiers and lasers. ? 2014 Society of Photo-Optical Instrumentation Engineers.Accession Number: 20141417538971 -
Record 184 of
Title:Exposure fusion using boosting Laplacian pyramid
Author(s):Shen, Jianbing(1); Zhao, Ying(1); Yan, Shuicheng(2); Li, Xuelong(3)Source: IEEE Transactions on Cybernetics Volume: 44 Issue: 9 DOI: 10.1109/TCYB.2013.2290435 Published: September 2014Abstract:This paper proposes a new exposure fusion approach for producing a high quality image result from multiple exposure images. Based on the local weight and global weight by considering the exposure quality measurement between different exposure images, and the just noticeable distortion-based saliency weight, a novel hybrid exposure weight measurement is developed. This new hybrid weight is guided not only by a single image's exposure level but also by the relative exposure level between different exposure images. The core of the approach is our novel boosting Laplacian pyramid, which is based on the structure of boosting the detail and base signal, respectively, and the boosting process is guided by the proposed exposure weight. Our approach can effectively blend the multiple exposure images for static scenes while preserving both color appearance and texture structure. Our experimental results demonstrate that the proposed approach successfully produces visually pleasing exposure fusion images with better color appearance and more texture details than the existing exposure fusion techniques and tone mapping operators. ? 2013 IEEE.Accession Number: 20143518111017 -
Record 185 of
Title:An improved corner detection algorithm for image sequence
Author(s):Yan, Minqi(1); Zhang, Bianlian(2); Guo, Min(1); Tian, Guangyuan(1); Liu, Feng(1); Huo, Zeng(1)Source: Proceedings of SPIE - The International Society for Optical Engineering Volume: 9301 Issue: DOI: 10.1117/12.2071559 Published: 2014Abstract:A SUSAN corner detection algorithm for a sequence of images is proposed in this paper, The correlation matching algorithm is treated for the coarse positioning of the detection area, after that, SUSAN corner detection is used to obtain interesting points of the target. The SUSAN corner detection has been improved. For the situation that the points of a small area are often detected as corner points incorrectly, the neighbor direction filter is applied to reduce the rate of mistakes. Experiment results show that the algorithm enhances the anti-noise performance, improve the accuracy of detection. ? 2014 SPIE.Accession Number: 20150800551963 -
Record 186 of
Title:Femtoseoncd laser-induced ablation regimes and thresholds in a nickel-based superalloy
Author(s):Zhang, Wei(1); Feng, Qiang(2); Cheng, Guanghua(3); Zhang, Xiaobing(1)Source: Guangxue Xuebao/Acta Optica Sinica Volume: 34 Issue: 12 DOI: 10.3788/AOS201434.1232001 Published: December 10, 2014Abstract:Femtosecond laser-induced ablation regimes and ablation thresholds of single-crystal nickel-based superalloy are investigated by means of microstructure on machined surface and trench as a function of laser fluence of 0~12.8 J/cm2 and the number of pulses of 0~8000. Two distinct ablation regimes (no-melting and melting ablation regime) are observed, dependent on the incident laser fluence. The ablation threshold fluences for these two ablation regimes are determined to be 0.23 J/cm2 and 1.21 J/cm2 in the superalloy. And the incubation factors for these two ablation regimes are determined to be 0.90 and 0.92. Furthermore, the relationship between both ablation regimes and ablation thresholds and their parametric dependence is established. The experimental results have practical guiding for processing nickel-based aviation of no recast layer and micro-cracks. ?, 2014, Chinese Optical Society. All right reserved.Accession Number: 20145300387472 -
Record 187 of
Title:Coded aperture spectral data restoration based on two-step iterative shrinkage/threshold
Author(s):Li, Yun(1,2); Hu, Bing-Liang(1); Wang, Shuang(1); Li, Ran(1); Shi, Da-Lian(1,2)Source: Guang Pu Xue Yu Guang Pu Fen Xi/Spectroscopy and Spectral Analysis Volume: 34 Issue: 3 DOI: 10.3964/j.issn.1000-0593(2014)03-0847-04 Published: March 2014Abstract:Coded aperture imaging spectrometer based on the concept of compressed sensing can acquire the spectral diagram of object. Coded aperture spectral data restoration reconstructs three-dimensional data cube from two-dimensional coded image. The two-step iterative shrinkage/thresholding algorithms were derived from the iterative shrinkage threshold algorithm and weighted iterative shrinkage algorithm. Recovering coded aperture spectral data using the two-step iterative shrinkage/thresholding algorithms obtained the three-dimensional spectral data cube successfully.Accession Number: 20141217481910 -
Record 188 of
Title:GA-SIFT: A new scale invariant feature transform for multispectral image using geometric algebra
Author(s):Li, Yanshan(1); Liu, Weiming(2); Li, Xiaotang(3); Huang, Qinghua(4); Li, Xuelong(5)Source: Information Sciences Volume: 281 Issue: DOI: 10.1016/j.ins.2013.12.022 Published: October 10, 2014Abstract:Feature analysis plays an important role in many multispectral image applications and scale invariant feature transform (SIFT) has been successfully applied for extraction of image features. However, the existing SIFT algorithms cannot extract features from multispectral images directly. This paper puts forward a novel algorithmic framework based on the SIFT for multispectral images. Firstly, with the theory of the geometric algebra (GA), a new representation of multispectral image including spatial and spectral information is put forward and discussed. Secondly, a new method for obtaining the scale space of the multispectral image is proposed. Thirdly, following the procedures of the SIFT, the GA based difference of Gaussian images are computed and the keypoints can be detected in the GA space. Fourthly, the feature points are finally detected and described in the mathematical framework of the GA. Finally, the comparison results show that the GA-SIFT outperforms some previously reported SIFT algorithms in the feature extraction from a multispectral image, and it is comparable with its counterparts in the feature extraction of color images, indicating good performance in various applications of image analysis. ? 2014 Elsevier Inc. All rights reserved.Accession Number: 20143117996573 -
Record 189 of
Title:Research on the low light level image enhancement algorithm based on ICCD
Author(s):Su, Yu(1); Zhao, Hui(1); Fan, Xuewu(1); Feng, Liangjie(1); Li, Ailing(1)Source: Guangxue Xuebao/Acta Optica Sinica Volume: 34 Issue: DOI: 10.3788/AOS201434.s210005 Published: December 1, 2014Abstract:The key to realize low light level imaging lies in the use of intensified charge coupled device (ICCD) which has a sensitive respond to very low light environment. However, even with the ICCD, the bad lighting condition and very low level optical radiation can make the image quality have a big drop compared with the traditional imaging environment, which severely limits the application of low light level image. Therefore, to improve the quality of low light level image, the characteristics of low light level image are firstly analyzed and then a comprehensive image enhancement algorithm is proposed. The outdoor experiments have been designed and the results demonstrate the effectiveness of the proposed algorithms. It is worth noting that when the radiance level decreases to smaller than 0.7 lx, the algorithm is still effective. ?, 2014, Guangxue Xuebao/Acta Optica Sinica. All right reserved.Accession Number: 20145300387757 -
Record 190 of
Title:Spectroscopic and thermal properties of Yb3+ doped TeO2–Bi2O3–Nb2O5 based tellurite glasses
Author(s):Lin, She-Bao(1,2); Wang, Peng-Fei(1); She, Jiang-Bo(1); Guo, Hai-Tao(1); Xu, Shen-Nuo(1,2); Zhao, Peng-Fei(1,2); Yu, Cheng-Long(3); Liu, Chun-Xiao(4); Peng, Bo(1,5)Source: Journal of Luminescence Volume: 153 Issue: DOI: 10.1016/j.jlumin.2014.02.031 Published: September 2014Abstract:Series of (94%–x) TeO2–6% Bi2O3–x Nb2O5 (x=10, 12.5, 15, 17.5 and 20 mol%) glasses doped with Yb2O3 were prepared by the melt-quenching method. Their emission cross-sections, fluorescence lifetimes, gain and thermal properties were investigated by the absorption spectra, the fluorescence decay curves and differential scanning calorimetry (DSC), respectively. The results show that the glass with 15 mol% Nb2O5 possesses the largest emission cross-section of 1.36 pm2, the longest fluorescence lifetime of 0.96 ms and the highest gain coefficient of 1.31 ms pm2; also the glass has excellent thermal properties, for which the value of ?T (=Tx?Tg) reaches up to 144 °C. These indicate that this tellurite glass may have potential application as Yb2O3 doped gain medium for solid lasers. ? 2014 Elsevier B.V.Accession Number: 20204909575906 -
Record 191 of
Title:Bright and dark square pulses generated from a graphene-oxide mode-locked ytterbium-doped fiber laser
Author(s):Lin, Rong-Yong(1); Wang, Yong-Gang(2); Yan, Pei-Guang(1); Zhang, Ge-Lin(1); Zhao, Jun-Qing(1); Li, Hui-Quan(1); Huang, Shi-Sheng(1); Cao, Guang-Zhong(3); Duan, Ji-An(4)Source: IEEE Photonics Journal Volume: 6 Issue: 3 DOI: 10.1109/JPHOT.2014.2319099 Published: June 2014Abstract:The observation of the bright pulses and dark square pulses in a graphene-oxide saturable absorber (GOSA) passively mode-locked ytterbium-doped fiber laser has been investigated experimentally. Bright pulses are achieved at a pump power of ～200 mW. However, the dark-square-pulse generation starts at a much higher pump power of ～450 mW. At the maximum pump power of 600 mW, the dark-square-pulse bunches and harmonic mode locking (HML) can be also obtained by tuning the polarization controller (PC) to different orientations. It is the first demonstration of the bunches and HML of dark square pulses in a GOSA passively mode-locked ytterbium-doped fiber laser with large normal dispersion cavity. ? 2014 IEEE.Accession Number: 20142217758751 -
Record 192 of
Title:Exact analytical solution for the mutual compensation of astigmatism using curved mirrors in a folded resonator laser
Author(s):Wen, Qiao(1,2); Liang, Guowen(1,2); Zhang, Xiaojun(1,2); Liang, Zongsen(1,2); Wang, Yonggang(3); Li, Ji(1); Niu, Hanben(1)Source: IEEE Photonics Journal Volume: 6 Issue: 6 DOI: 10.1109/JPHOT.2014.2366160 Published: December 2014Abstract:For the first time, to the best of our knowledge, analytical expressions for mutually compensating the curved mirror astigmatism in the two terminal arms of a folded resonator are deduced and experimentally verified. The analytical expressions are derived using the theory of the propagation and transformation of Gaussian beams under few assumptions. Our exact analytical expressions describe the necessary and sufficient conditions for simultaneously compensating astigmatism in two arms of a sequence of two off-axis curved mirrors. The theoretical results indicate that, when the astigmatism compensation expressions are satisfied, the astigmatism introduced by a folded curved mirror can be mutually compensated by another folded curved mirror, even if there is no additional Brewster element inside the cavity. The astigmatism can only be successfully eliminated by using a pair of concave mirrors or convex mirrors. Our analytical expressions can be used to design astigmatically compensated folded resonators without a Brewster element. A typical side-pumped z-shaped cavity Nd:YAG laser is employed to demonstrate the astigmatic compensation. Experimental measurements of the pattern of the laser output beam show that not only the spot intensity profile deformation but, in addition, the phase distortion in the two terminal arms can be simultaneously compensated completely in the cavity, which is in good agreement with the analytical predictions. ? 2014 IEEE.Accession Number: 20145200360824