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ACTIVE VIBRATION CONTROL OF TWO-BEAM STRUCTURES 被引量:1
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作者 陈涛 王立刚 冯国锋 《Transactions of Nanjing University of Aeronautics and Astronautics》 EI 2013年第2期193-201,共9页
The wave propagation approach is presented to research the active vibration control of two-beam structures.Considering the continuity of the generalized displacement and the equilibrium of the generalized force at the... The wave propagation approach is presented to research the active vibration control of two-beam structures.Considering the continuity of the generalized displacement and the equilibrium of the generalized force at the discontinuity,the wave reflection and transmission coefficients are calculated.Wave control is applied somewhere upstream or downstream to two-beam structures.Vibrations of two coupled beams per unit disturbance are investigated.The results show that wave control is efficient,and the influence of the thickness ratio of two-beam structures on control location is discussed. 展开更多
关键词 two-beam STRUCTURES VIBRATION CONTROL REFLECTION COEFFICIENTS TRANSMISSION COEFFICIENTS
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Identity Authentication Based on Two-Beam Interference
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作者 Wenqi He Xiang Peng 《Journal of Computer and Communications》 2014年第4期31-38,共8页
A two-factor identity authentication method on the basis of two-beam interference was presented. While verifying a user’s identity, a specific “phase key” as well as a corresponding “phase lock” are both mandator... A two-factor identity authentication method on the basis of two-beam interference was presented. While verifying a user’s identity, a specific “phase key” as well as a corresponding “phase lock” are both mandatory required for a successful authentication. Note that this scheme can not only check the legality of the users, but also verify their identity levels so as to grant them hierarchical access permissions to various resources of the protected systems or organizations. The authentication process is straightforward and could be implemented by a hybrid optic-electrical system. However, the system designing procedure involves an iterative Modified Phase Retrieval Algorithm (MPRA) and can only be achieved by digital means. Theoretical analysis and simulations both validate the effectiveness of our method. 展开更多
关键词 OPTICAL INFORMATION SECURITY OPTICAL AUTHENTICATION two-beam INTERFERENCE
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Large-area straight,regular periodic surface structures produced on fused silica by the interference of two femtosecond laser beams through cylindrical lens 被引量:9
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作者 Long Chen Kaiqiang Cao +5 位作者 Yanli Li Jukun Liu Shian Zhang Donghai Feng Zhenrong Sun Tianqing Jia 《Opto-Electronic Advances》 SCIE EI 2021年第12期34-42,共9页
Inhomogeneity and low efficiency are two important factors that limit the application of laser-induced periodic surface structures(LIPSSs),especially on glass surfaces.In this study,two-beam interference(TBI)of femtos... Inhomogeneity and low efficiency are two important factors that limit the application of laser-induced periodic surface structures(LIPSSs),especially on glass surfaces.In this study,two-beam interference(TBI)of femtosecond lasers was used to produce large-area straight LIPSSs on fused silica using cylindrical lenses.Compared with those produced us-ing a single circular or cylindrical lens,the LIPSSs produced by TBI are much straighter and more regular.Depending on the laser fluence and scanning velocity,LIPSSs with grating-like or spaced LIPSSs are produced on the fused silica sur-face.Their structural colors are blue,green,and red,and only green and red,respectively.Grating-like LIPSS patterns oriented in different directions are obtained and exhibit bright and vivid colors,indicating potential applications in surface coloring and anti-counterfeiting logos. 展开更多
关键词 laser-induced periodic surface structures two-beam interference structural coloring fused silica cylindrical lens
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Simultaneous acceleration of two kinds of ion beams in the RISP 被引量:1
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作者 Siwon Jang Eun-San Kim 《Nuclear Science and Techniques》 SCIE CAS CSCD 2019年第6期70-77,共8页
The Rare Isotope Science Project (RISP) is a research complex consisting of a heavy-ion accelerator, which contains a front-end system, a super-conducting linear accelerator, an isotope separator online (ISOL) system,... The Rare Isotope Science Project (RISP) is a research complex consisting of a heavy-ion accelerator, which contains a front-end system, a super-conducting linear accelerator, an isotope separator online (ISOL) system, and an in-flight system. The original purpose of the post-linear-accelerator (post-linac) section was to accelerate either a stable driver beam derived from an electron cyclotron resonance ion source, or an unstable rare-isotope beam from an ISOL system. The post-linac lattice has now been redesigned using a novel and improved acceleration concept that allows the simultaneous acceleration of both a stable driver beam and a radioisotope beam. To achieve this, the post-linac lattice is set for a mass-to-charge ratio (A/q) that is the average of the two beams. The performance of this simultaneous two-beam acceleration is here assessed using two ion beams: 58Ni^8+ and 132Sn^20+. A beam dynamics simulation was performed using the TRACK and TraceWin codes. The resultant beam dynamics for the new RISP post-linac lattice design are examined. We also estimate the effects of machine errors and their correction on the post-linac lattice. 展开更多
关键词 Linear ACCELERATOR SIMULTANEOUS two-beam ACCELERATION HEAVY-ION ACCELERATOR BEAM dynamics
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Photorefractive Effect in a CdS Nanoparticlessensitized Polymer Composite
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作者 丁莉芸 姜德生 《Journal of Wuhan University of Technology(Materials Science)》 SCIE EI CAS 2007年第4期638-642,共5页
The photorefractive (PR) performance of an organic/inorganic hybrid polymer composite sensitized by CdS nanoparticles, combining poly(N-vinylcarbazole) (PVK), the second-order optically nonlinear chromophore 1-n... The photorefractive (PR) performance of an organic/inorganic hybrid polymer composite sensitized by CdS nanoparticles, combining poly(N-vinylcarbazole) (PVK), the second-order optically nonlinear chromophore 1-n-butoxy-2-methyl-(4-p-nitropheylazo)benzene (BMNPAB) and 9-ethylcarbazole (ECZ) was studied. It was confirmed that the CdS colloidal particles had a nanoscale size and quantum confinement effect adopting transmission electron microscopy and UV-Vis absorption spectroscopy. The addition of CdS nanoparticles as a photosensitizer in PVK will be significant enhancement of photoconductivity because of the high photocharge generation quantum efficiency and high charge transport to conducting polymer. The polymer composite film exhibited PR effect with a method of two-beam coupling experiment. And an asymmetric two. beam coupling gain of 45.8 cm^-1 without applied electric filed is obtained at 632.8 nm wavelength. 展开更多
关键词 photorefi-active polymer PVK/CdS nanocomposite PHOTOCONDUCTIVITY two-beam coupling
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Rotation Measurement Using Speckle Photography with LiNbO3 Crystal: Theoretical and Experimental Analysis
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作者 Nasser A. Moustafa H. Elgebaly 《Optics and Photonics Journal》 2021年第10期441-452,共12页
Photorefractive crystals present varied features charming presence, such as high resolution, and normal handling. Depending on the portability of erasing images, photorefractive crystals are convenient for read-write ... Photorefractive crystals present varied features charming presence, such as high resolution, and normal handling. Depending on the portability of erasing images, photorefractive crystals are convenient for read-write implementations and hence find potential use in speckle photography, speckle interferometry, image processing and holography. A two-beam coupling arrangement using a LiNbO3 crystal as a recording medium for real-time rotation measurement using the coherent and low-power laser source is presented in this paper. A speckle photography technique is advanced for the measurement of a small rotation of a transmitted glass slide sample. New theoretical analysis is formulated for a general case of a slide rotation. Experimental studies are carried out to verify the outcome of the theoretical predictions and accuracy of measurement. Uncertainty of rotation measurement is studied and quantified. The proposed technique is a simple, attractive and alternative method for fringe analysis. The method promises a high degree of accuracy and increased range for rotation measurement in real-time. 展开更多
关键词 Speckle Photgraphy Photo-Refractive Materials two-beam Coupling Measurement Uncertainty Tilt Measurement
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TEMPERATURE DEPENDENCE OF TWO-BEAM COUPLING IN Ce: LiNbO_3 CRYSTAL 被引量:2
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作者 刘劲松 石顺祥 +2 位作者 李铭华 赵业权 徐玉恒 《Chinese Science Bulletin》 SCIE EI CAS 1992年第9期718-721,共4页
The effect of temperature on photorefractive process is a significant problem inphotorefractive nonlinear optics. The temperature dependence of photoretiactive effect in semiinsulating semiconductive material Cr: GaAs... The effect of temperature on photorefractive process is a significant problem inphotorefractive nonlinear optics. The temperature dependence of photoretiactive effect in semiinsulating semiconductive material Cr: GaAs was investigated by CHENG Li-jen et al., and they thought that the band gap of conventional oxide photorefractive crystal was too wide, so it is difficult to observe the temperature dependence of photorefractive effect in a general experimental condition. But the point of view has been proved not true by our experiment 展开更多
关键词 PHOTOREFRACTIVE nonlinear OPTICS two-beam coupling temperature characteristic PHOTOREFRACTIVE OXIDE CRYSTAL doped-LiNbO3
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Regular uniform large-area subwavelength nanogratings fabricated by the interference of two femtosecond laser beams via cylindrical lens 被引量:2
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作者 曹凯强 陈龙 +2 位作者 程可 孙真荣 贾天卿 《Chinese Optics Letters》 SCIE EI CAS CSCD 2020年第9期79-83,共5页
Inhomogeneity and low efficiency are two important factors that hinder the wide application of laser-induced periodic surface structures. Two-beam interference is commonly used to fabricate gratings with interference ... Inhomogeneity and low efficiency are two important factors that hinder the wide application of laser-induced periodic surface structures. Two-beam interference is commonly used to fabricate gratings with interference periods. This study reports regular and uniform periodic ripples fabricated efficiently by the interference of two femtosecond laser beams via a cylindrical lens. The interference period is adjusted to be an integer multiple of the wavelength of a surface plasmon polariton. Regular and uniform subwavelength nanogratings(RUSNGs)on a silicon wafer of a diameter of 100 mm are fabricated with a scanning velocity of 6–9 mm/s. Bright and pure colors(including purple, blue, and red) are demonstrated on different patterns covered with RUSNGs. 展开更多
关键词 subwavelength nanogratings two-beam interference surface plasmon polariton structural coloring
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Laser interference fabrication of large-area functional periodic structure surface 被引量:2
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作者 Lei WANG Zi-Han WANG +1 位作者 Yan-Hao YU Hong-Bo SUN 《Frontiers of Mechanical Engineering》 SCIE CSCD 2018年第4期493-503,共11页
Functional periodic structures have attracted significant interest due to their natural capabilities in regulating surface energy, surface effective refractive index, and diffraction. Several technologies are used for... Functional periodic structures have attracted significant interest due to their natural capabilities in regulating surface energy, surface effective refractive index, and diffraction. Several technologies are used for the fabrication of these functional structures. The laser interference technique in particular has received attention because of its simplicity, low cost, and high-efficiency fabrication of large-area, micro/nanometer-scale, and periodically patterned structures in air conditions. Here, we reviewed the work on laser interference fabrication of large-area functional periodic structures for antireflection, self-cleaning, and superhydrophobicity based on our past and current research. For the common cases, four-beam interference and multi-exposure of two-beam interference were emphasized for their setup, structure diversity, and various applications for antireflection, self-cleaning, and superhydrophobicity. The relations between multi-beam interference and multi-exposure of two-beam interference were compared theoretically and experimentally. Nanostructures as a template for growing nanocrystals were also shown to present future possible applications in surface chemical control. Perspectives on future directions and applications for laser interference were presented. 展开更多
关键词 laser interference four-beam interference multi-exposure of two-beam interference additive fabrication
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Broadening of Angular Response Range With High Gain in Doped Lithium Niobate Crystals
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作者 赵桦 张景文 +3 位作者 孙万钧 许克彬 李铭华 徐玉恒 《Chinese Science Bulletin》 SCIE EI CAS 1994年第18期1578-1582,共5页
Research on photorefractive effect grew unceasingly in the past two decades. A special application of the effect, light amplification, has drawn much attention recently. In order to improve the gain coefficient of pho... Research on photorefractive effect grew unceasingly in the past two decades. A special application of the effect, light amplification, has drawn much attention recently. In order to improve the gain coefficient of photorefractive crystals, methods of adjusting dopants and their concentration or special techniques are adopted 展开更多
关键词 optical AMPLIFICATION two-beam coupling LIGHT-INDUCED scattering with large angle self- enhancement.
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