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2014

Record 85 of

Title:Multi-frame super-resolution reconstruction algorithm based on diffusion tensor regularization term

Author(s):Zhao, Xiao Dong(1,2); Zhou, Zuo Feng(1); Cao, Jian Zhong(1); Ren, Long(1); Liu, Guang Sen(1); Wang, Hua(1); Wu, Deng Shan(1); Tan, Jia Hai(1)
Source: Applied Mechanics and Materials Volume: 543-547 Issue: DOI: 10.4028/www.scientific.net/AMM.543-547.2828 Published: 2014
Abstract:This paper presents a multi-frame super-resolution (SR) reconstruction algorithm based on diffusion tensor regularization term. Firstly, L1-norm structure is used as data fidelity term, anisotropic diffusion equation with directional smooth characteristics is introduced as a prior knowledge to optimize reconstruction result. Secondly, combined with shock filter, SR reconstruction energy functional is established. Finally, Euler-Lagrange equation based on nonlinear diffusion model is exported. Simulation results validate that the proposed algorithm enhances image edges and suppresses noise effectively, which proves better robustness. ? (2014) Trans Tech Publications, Switzerland.
Accession Number: 20141717625228
Record 86 of

Title:Indoor test method of attitude measurement accuracy of photoelectric theodolite

Author(s):Tian, Liude(1,2); Liu, Chaohui(1); Zhao, Jianke(1); Duan, Yanxuan(1,2); Pan, Liang(1); Zhao, Huaixue(1); Duan, Jiong(1); Long, Jiangbo(1); Wang, Zhengfeng(1)
Source: Guangxue Xuebao/Acta Optica Sinica Volume: 34 Issue: 8 DOI: 10.3788/AOS201434.0812002 Published: August 10, 2014
Abstract:In order to realize indoor test and evaluation of attitude measurement accuracy of range optical attitude measurement equipment, some research work has been done. The principle of intersection surveying the attitude of spatial axisymmetric target with photoelectric theodolites is introduced. The device is introduced to simulate the attitude of infinite object indoor, which is composed of measurement rack, collimator, light source, and targets with different angles. Precise mathematical model is established, which is relation with target attitude angle and azimuth and elevation of target feature points. Firstly, several feature points on the target are measured with high precision theodolite. Secondly, according to the above mathematical model, the target attitude is fitted by using the least square method, then, the target attitude angle is got. It has been proved that the calibration precision can reach 0.05°. Consider the calibration results as true value of the target attitude angle, dynamic measurements are performed on the same target by using photoelectric theodolite and attitude measurement error of the theodolite can be obtained in comparsion with two measurement results.
Accession Number: 20143700064775
Record 87 of

Title:A method which can enhance the optical -centering accuracy

Author(s):Zhang, Xue-Min(1,2); Zhang, Xue-Jun(2); Dai, Yi-Dan(2); Yu, Tao(1,2); Duan, Jia-You(1); Li, Hua(1)
Source: Proceedings of SPIE - The International Society for Optical Engineering Volume: 9282 Issue: DOI: 10.1117/12.2069793 Published: 2014
Abstract:Optical alignment machining is an effective method to ensure the co-axiality of optical system. The co-axiality accuracy is determined by optical-centering accuracy of single optical unit, which is determined by the rotating accuracy of lathe and the optical-centering judgment accuracy. When the rotating accuracy of 0.2um can be achieved, the leading error can be ignored. An axis-determination tool which is based on the principle of auto-collimation can be used to determine the only position of centerscope is designed. The only position is the position where the optical axis of centerscope is coincided with the rotating axis of the lathe. Also a new optical-centering judgment method is presented. A system which includes the axis-determination tool and the new optical-centering judgment method can enhance the optical-centering accuracy to 0.003mm. ? 2014 SPIE.
Accession Number: 20150800543944
Record 88 of

Title:Lung nodule detection and segmentation algorithm based on average intensity projection and shift Gaussian model

Author(s):Qiu, Shi(1,2); Wen, Desheng(1); Wang, Lei(3)
Source: Yi Qi Yi Biao Xue Bao/Chinese Journal of Scientific Instrument Volume: 35 Issue: 11 DOI: Published: November 1, 2014
Abstract:Aiming at the problem that in CT image the blood vessels and nodules may connected that leads to segmentation difficulty, a novel nodule segmentation algorithm is proposed based on average intensity projection (AIP) and shift Gaussian model. Firstly, the AIP method is employed on a 2D CT image to generate an AIP image with local 3D features. Secondly, the region of interest (ROI) is obtained by performing threshold segmentation and morphology transformation on the AIP image. Finally, through establishing the shift Gaussian model the nodules are accurately extracted. The experiments on 30 CT images with blood vessel connection were conducted, the results show that the area overlap measure (AOM) reaches 91% between the proposed algorithm and the professional doctor manual segmentation; the proposed algorithm can achieve effect segmentation of lung nodules with blood vessel connection; however, there is still a risk of miss detection for the lung nodules with weak grey scale and small volume, which needs to be further studied. ?, 2014, Science Press. All right reserved.
Accession Number: 20145200366123
Record 89 of

Title:A multi-focus image adaptive fusion method based on comprehensive index

Author(s):Lu, Hao(1,2); Song, Zongxi(1); Gao, Wei(1); Wang, Qi(1,2); Xi, Jiangbo(1,2)
Source: Proceedings of SPIE - The International Society for Optical Engineering Volume: 9284 Issue: DOI: 10.1117/12.2069158 Published: 2014
Abstract:As the focusing range of optical imaging system is generally limited, it is difficult to make all the objects of the same scene clearly shown in one image. Besides, a case usually rose that the fused image with a high entropy, however, is not satisfying for vision effect. In this paper, a new method of multi-focus image fusion based on adaptive dividing blocks using comprehensive index was proposed, in which the comprehensive index was on basis of spatial frequency and entropy. The comprehensive index is better with the higher spatial frequency and entropy. Firstly, the registered original images were divided into a series of blocks of which the sizes were proper and the same, and then the comprehensive index for each block of source images was calculated as the focus criterion function to select an optimal block for each corresponding block of the fused image. In view of the relevance between pixel and pixel in one image, the optimal blocks selected were fused with a global fusion function. Furthermore, the sum-modified-Laplacian of fused image was used as the measure function to supervise the adaptive blocking, in which the optimal block was obtained when SML of the fused image had reached a high value or the iteration had achieved the specified numbers. Finally, the optimal size of the sub-block was automatically obtained, which was used to fuse the source images. As it was shown in the experimental results, the proposed method which was simple, but more effective compared with the traditional multiscale decomposing methods such as wavelet transform, wavelet packet transform, contourlet transform and so on. At the same time, the proposed method was also superior to the method in the literature for it could remove boundary discontinuities between image blocks. Contemporarily, much more details and edges information of the source images were reserved in the fused image.
Accession Number: 20150800545787
Record 90 of

Title:Laser pulse propagation and enhanced energy coupling to fast electrons in dense plasma gradients

Author(s):Gray, R.J.(1); Carroll, D.C.(1,2); Yuan, X.H.(1,5); Brenner, C.M.(1,2); Burza, M.(3); Coury, M.(1); Lancaster, K.L.(2); Lin, X.X.(4); Li, Y.T.(4); Neely, D.(1,2); Quinn, M.N.(1); Tresca, O.(1); Wahlstr?m, C.-G.(3); McKenna, P.(1)
Source: New Journal of Physics Volume: 16 Issue: DOI: 10.1088/1367-2630/16/11/113075 Published: November 28, 2014
Abstract:Laser energy absorption to fast electrons during the interaction of an ultraintense (1020 Wcm-2), picosecond laser pulse with a solid is investigated, experimentally and numerically, as a function of the plasma density scale length at the irradiated surface. It is shown that there is an optimum density gradient for efficient energy coupling to electrons and that this arises due to strong self-focusing and channeling driving energy absorption over an extended length in the preformed plasma. At longer density gradients the laser filaments, resulting in significantly lower overall energy coupling. As the scale length is further increased, a transition to a second laser energy absorption process is observed experimentally via multiple diagnostics. The results demonstrate that it is possible to signi ficantly enhance laser energy absorption and coupling to fast electrons by dynamically controlling the plasma density gradient. ? 2014 IOP Publishing Ltd and Deutsche Physikalische Gesellschaft.
Accession Number: 20145100345892
Record 91 of

Title:Design and fabrication of tapered microfiber waveguide with good optical and mechanical performance

Author(s):Ma, Cheng-Ju(1,2,3); Ren, Li-Yong(1); Xu, Yi-Ping(1,2); Wang, Ying-Li(1); Liang, Jian(1); Qu, En-Shi(1)
Source: Journal of Modern Optics Volume: 61 Issue: 8 DOI: 10.1080/09500340.2014.909541 Published: May 4, 2014
Abstract:In this paper, the inherent dependence of optical and mechanical characteristics of tapered microfiber waveguide on its contour profile is studied. Both theoretical analysis and experimental investigation are given. In theory, the optimal profile parameters of the tapered microfiber are proposed to improve the microfiber performance, where it is better to make the tapered microfiber keep two longer than 5-mm-long transition regions which have a decaying exponential profile. And the uniform waist diameter of the tapered microfiber should be more than 600 nm and less than 1 μm. In this case, the microfiber indicates several favorable advantages, such as low loss, strong evanescent field and relatively shorter transition region. In experiment, according to the profile parameters we proposed, we successfully fabricated a tapered microfiber with a low loss of 0.05 dB in air and 0.8 dB on a MgF 2 substrate at the wavelength of 1550 nm, and it has low surface roughness. ? 2014 Taylor & Francis.
Accession Number: 20142117754540
Record 92 of

Title:CFRP variable curvature mirror used for realizing non-moving-element optical zoom imaging

Author(s):Zhao, Hui(1); Fan, Xuewu(1); Pang, Zhihai(1); Ren, Guorui(1); Wang, Wei(1); Xie, Yongjie(1); Ma, Zhen(1); Du, Yunfei(1); Su, Yu(1); Wei, Jingxuan(2)
Source: Proceedings of SPIE - The International Society for Optical Engineering Volume: 9293 Issue: DOI: 10.1117/12.2069856 Published: 2014
Abstract:In recent years, how to eliminate moving elements while realizing optical zoom imaging has been paid much attention. Compared with the conventional optical zooming techniques, removing moving elements would bring in many benefits such as reduction in weight, volume and power cost and so on. The key to implement non-moving-element optical zooming lies in the design of variable curvature mirror (VCM). In order to obtain big enough optical magnification, the VCM should be capable of generating a large variation of saggitus. Hence, the mirror material should not be brittle, in other words the corresponding ultimate strength should be high enough to ensure that mirror surface would not be broken during large curvature variation. Besides that, the material should have a not too big Young's modulus because in this case less force is required to generate a deformation. Among all available materials, for instance SiC, Zerodur and et.al, CFRP (carbon fiber reinforced polymer) satisfies all these requirements and many related research have proven this. In this paper, a CFRP VCM is designed, fabricated and tested. With a diameter of 100mm, a thickness of 2mm and an initial curvature radius of 1740mm, this component could change its curvature radius from 1705mm to 1760mm, which correspond to a saggitus variation of nearly 23μm. The work reported further proves the suitability of CFRP in constructing variable curvature mirror which could generate a large variation of saggitus. ? 2014 SPIE.
Accession Number: 20150800554701
Record 93 of

Title:Abnormal ripple patterns with enhanced regularity and continuity in a bulk metallic glass induced by femtosecond laser irradiation

Author(s):Zhang, W.(1,2); Cheng, G.(3); Hui, X.D.(1); Feng, Q.(1,4)
Source: Applied Physics A: Materials Science and Processing Volume: 115 Issue: 4 DOI: 10.1007/s00339-013-8062-z Published: June 2014
Abstract:Two types of abnormal ripple patterns: classical ripples (C-ripples) with continuous ridges and unclassical ripples (U-ripples) with regular micropores were investigated in a Zr-based bulk metallic glass (Zr-BMG) after femtosecond laser beam irradiation. U-ripples with a period of ～ 1,600 nm and the orientation nearly parallel to the polarization of laser beam were observed to form gradually on the top of C-ripples with the effective pulse number. Micropores created by the superposition of C-ripples and U-ripples had an average diameter of ～ 750 nm nearly equal to the period of C-ripples (～ 720 nm) and ran along parallel lines in the grooves of U-ripples. Both U-ripples and C-ripples in Zr-BMG showed significant microstructural differences comparing with those in a conventional Zr-based alloy with the same composition and processing conditions, including much more regular and continuous ridges. The results indicate that the amorphous structure in Zr-BMG plays a key role in the uniform morphology of laser-induced structures. ? 2013 Springer-Verlag Berlin Heidelberg.
Accession Number: 20142317782796
Record 94 of

Title:The design method of CGH for testing the Φ404, F2 primary mirror

Author(s):Xie, Nian(1,2); Duan, Xueting(1); Li, Hua(1)
Source: Proceedings of SPIE - The International Society for Optical Engineering Volume: 9280 Issue: DOI: 10.1117/12.2068031 Published: 2014
Abstract:In order to accurately test shape quality of the large diameter aspherical mirror, a kind of binary optical element called Computer generated holograms (CGHs) are widely used.The primary role of the CGHs is to generate any desired wavefronts to realize phase compensation. In this paper, the CGH design principle and design process are reviewed at first. Then an optical testing system for testing the aspheric mirror includes a computer generated hologram (CGH) and an imaging element (IE) is disposed. And an optical testing system only concludes a CGH is proposed too. The CGH is designed for measurement of an aspheric mirror (diameter=404mm, F-number=2). Interferometric simulation test results of the aspheric mirror show that the whole test system obtains the demanded high accuracy. When combined the CGH with an imaging element in the Aspheric Compensator, the smallest feature in the CGH should be decreased. The CGH can also be used to test freeform surface with high precision, it is of great significance to the development of the freeform surface. ? 2014 SPIE.
Accession Number: 20150800541544
Record 95 of

Title:FIVQ algorithm for interference hyper-spectral image compression

Author(s):Wen, Jia(1,2); Ma, Caiwen(2); Zhao, Junsuo(1)
Source: Optics Communications Volume: 322 Issue: DOI: 10.1016/j.optcom.2014.02.016 Published: July 1, 2014
Abstract:Based on the improved vector quantization (IVQ) algorithm [1] which was proposed in 2012, this paper proposes a further improved vector quantization (FIVQ) algorithm for LASIS (Large Aperture Static Imaging Spectrometer) interference hyper-spectral image compression. To get better image quality, IVQ algorithm takes both the mean values and the VQ indices as the encoding rules. Although IVQ algorithm can improve both the bit rate and the image quality, it still can be further improved in order to get much lower bit rate for the LASIS interference pattern with the special optical characteristics based on the pushing and sweeping in LASIS imaging principle. In the proposed algorithm FIVQ, the neighborhood of the encoding blocks of the interference pattern image, which are using the mean value rules, will be checked whether they have the same mean value as the current processing block. Experiments show the proposed algorithm FIVQ can get lower bit rate compared to that of the IVQ algorithm for the LASIS interference hyper-spectral sequences. ? 2014 Elsevier B.V.
Accession Number: 20141017435400
Record 96 of

Title:Tunable slow light based on plasmon-induced transparency in dual-stub-coupled waveguide

Author(s):Wang, Guoxi(1); Zhang, Wenfu(1); Gong, Yongkang(1); Liang, Jian(1)
Source: IEEE Photonics Technology Letters Volume: 27 Issue: 1 DOI: 10.1109/LPT.2014.2362293 Published: January 1, 2015
Abstract:We investigate the plasmon-induced transparency (PIT) effect in dual-stub-coupled metal-insulator-metal waveguide. The transmission line theory is employed to analyze the relationship between the transmission properties and geometrical parameters. It is found that by incorporating tunable refractive index materials with the proposed structure, a tunable PIT and slow light effect can be obtained in a constant stub separation design. The theoretical results show that a shift of 70 THz in the central wavelengths of transparency window can be obtained when the refractive index of the dielectric varies. In addition, the group index can be tuned from 24 to 36, which provides an effective method to adjust the slow light properties in the proposed waveguide. This letter opens up the possibility for the realization of tunable slow light devices in highly integrated optical circuits. ? 2014 IEEE.
Accession Number: 20145200364936