共查询到20条相似文献,搜索用时 15 毫秒
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A technique based on self-imaging at finite conjugates has been experimentally demonstrated for visualization of laser-induced photorefractive gratings in BSO. A simple model theory has been used to provide the correct rules of geometrical optics of self-imaging. A novel technique has been used for photoinducing the periodic structure. An application has been made to determine the harmonic components of the nonsinusoidal refractive index modulation in the BSO for a grating period of 10 m and for external DC voltages of 6.0 and 3.0 kV. The technique is directly applicable to the visualization and study of laser-induced gratings (LIG) in thin nonlinear optical media. 相似文献
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Abramson has demonstrated that by using the finite coherence properties of light, holograms can be constructed that allow one to visualize the path that a simulated light pulse takes through an optical system. We have demonstrated that using an alternate hologram construction and readout geometry, light with a very long coherence length can also be used to visualize light propagation. Experimental results showing well resolved time-sequence photographs of reflection, refraction, and diffraction in an optical system are given. 相似文献
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Investigation of flapping wings of insect are focused on low Reynolds number effect and the unsteady aerodynamic properties.
Interaction between flapping wing of insects and the air flow became one of important and fundamental research topics in micro
air vehicle. The present work is aim to investigate the flow behavior of flapping wings of tethered scarab beetle. The generation
mechanisms of velocity field and vortex formation are visualized with smoke-wire method. Tethered flight of the drone beetle
shows the motion with elastic deformation of flapping wing. Measured flapping frequency is about 71 Hz and its frequency is
higher than for dragonfly and butterfly. Beetle decreases negative lift by feathering motion in the upstroke process and increase
positive lift by effect of wake capture in the downstroke process. 相似文献
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For the detailed investigation of the 3D unsteady incompressible viscous separated fluid flows around a sphere (for 200≤Re≤700) and a circular cylinder (for 200≤Re≤400) the direct numerical simulation and 3D visualization are used. For 3D visualization of the fluid flows around a sphere
the definition of vortex core as a connected region containing two negative eigenvalues of theS
2+Ω
2 tensor is used (whereS
i,j andΩ
ij
are the rate of strain and the rate of rotation tensors). The formation mechanism of vortices in the sphere wake for Re=500
is described in detail. For 3D visualization of the fluid flows around a circular cylinder the 3D isosurfaces of the streamwise
component of vorticity ω
x
are used. 相似文献
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In the x-ray region the reflectivity of a superpolished surface strongly depends on its roughness. This effect may be used
to obtain a two-dimensional map of the roughness spatial distribution for flat surfaces with an average roughness height of
the order of one nanometer or less. The method described in the paper lies in the illumination of the sample by a highly collimated
x-ray beam, and a linear one-dimensional scanning of the sample with simultaneous registration of the specular component of
the reflected beam by multielement linear detector. This method may be used to monitor the surface quality of silicon semiconductor
wafers, computer hard disks, x-ray and laser mirror substrates etc. 相似文献
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The schlieren method is applied to visualizing the sound scattering ofa cylinder immersed in the liquids.Images of the echoes,caused by normal andoblique incidence from a cylinder,are obtained for two kinds of liquids:(1)theliquid is composed of a transparent liquid;and(2)the liquid is composed of twonon-mixable transparent liquids.It is found experimentally that the echo canbe caused by the discontinaites in the shadow zone.This fact is utilized to dem-onstrate the locus of the helical surface wave creeping along the surface of thecylinder.For such cases the three-dimensional image can be described by thismethod and has not to use the system with special appliances and complexalgorithm. 相似文献
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We study localized plasmons at the nanoscale (nano-plasmons) in graphene. The collective excitations of induced charge density modulations in graphene are drastically changed in the vicinity of a single impurity compared to graphene's bulk behavior. The dispersion of nano-plasmons depends on the number of electrons and the sign, strength and size of the impurity potential. Due to this rich parameter space the calculated dispersions are intrinsically multidimensional requiring an advanced visualization tool for their efficient analysis, which can be achieved with parallel rendering. To overcome the problem of analyzing thousands of very complex spatial patterns of nano-plasmonic modes, we take a combined visual and quantitative approach to investigate the excitations on the two-dimensional graphene lattice. Our visual and quantitative analysis shows that impurities trigger the formation of localized plasmonic excitations of various symmetries. We visually identify dipolar, quadrupolar and radial modes, and quantify the spatial distributions of induced charges. 相似文献
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