- 标题
- 摘要
- 关键词
- 实验方案
- 产品
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Demonstration of Scale-Invariant Rayleigh-Taylor Instability Growth in Laser-Driven Cylindrical Implosion Experiments
摘要： Rayleigh-Taylor instability growth is shown to be hydrodynamically scale invariant in convergent cylindrical implosions for targets that varied in radial dimension and implosion timescale by a factor of 3. The targets were driven directly by laser irradiation providing a short impulse, and instability growth at an embedded aluminum interface occurs as it converges radially inward by a factor of 2.25 and decelerates on a central foam core. Late-time growth factors of 14 are observed for a single-mode m ? 20 azimuthal perturbation at both scales, despite the differences in laser drive conditions between the experimental facilities, consistent with predictions from radiation-hydrodynamics simulations. This platform enables detailed investigations into the limits of hydrodynamic scaling in high-energy-density systems.
关键词： high-energy-density physics,hydrodynamic scaling,laser-driven implosions,Rayleigh-Taylor instability
更新于2025-09-23 15:21:01
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The Role of Rayleigh-Wood Anomalies and Surface Plasmons in Optical Enhancement for Nano-Gratings
摘要： We propose and report on the design of a 1-D metallo-dielectric nano-grating on a GaAs substrate. We numerically study the impact of grating period, slit and wire widths, and irradiating angle of incidence on the optical response. The optimal wire width, w = 160 nm, was chosen based on previous results from investigations into the influence of wire width and nano-slit dimensions on optical and electrical enhancements in metal-semiconductor-metal photodetectors. In this present project, resonant absorption and reflection modes were observed while varying the wire and nano-slit widths to study the unique optical modes generated by Rayleigh-Wood anomalies and surface plasmon polaritons. We observed sharp and diffuse changes in optical response to these anomalies, which may potentially be useful in applications such as photo-sensing and photodetectors. Additionally, we found that varying the slit width produced sharper, more intense anomalies in the optical spectrum than varying the wire width.
关键词： Rayleigh-Wood anomalies,photo-sensing,nano-optics,plasmonics
更新于2025-09-23 15:21:01
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Nonlinear Optics || Stimulated Brillouin and Stimulated Rayleigh Scattering
摘要： We saw in Section 8.1 that light scattering can occur only as the result of fluctuations in the optical properties of a material system. A light-scattering process is said to be spontaneous if the fluctuations (typically in the dielectric constant) that cause the light-scattering are excited by thermal or by quantum-mechanical zero-point effects. In contrast, a light-scattering process is said to be stimulated if the fluctuations are induced by the presence of the light field. Stimulated light scattering is typically very much more efficient than spontaneous light scattering. For example, approximately one part in 105 of the power contained in a beam of visible light would be scattered out of the beam by spontaneous scattering in passing through 1 cm of liquid water. In this chapter, we shall see that when the intensity of the incident light is sufficiently large, essentially 100% of a beam of light can be scattered in a 1-cm path as the result of stimulated scattering processes.
关键词： Stimulated Rayleigh scattering,electrostriction,Stimulated Brillouin scattering,optical properties,light scattering
更新于2025-09-23 15:21:01
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Design of an innovative and self-adaptive-smart algorithm to investigate the structural integrity of a rail track using Rayleigh waves emitted and sensed by a fully non-contact laser transduction system
摘要： The focus of this study is on locating surface and sub-surface defects that occur in rail tracks using Rayleigh waves that were emitted and sensed by a fully non-contact laser transduction system. As the quality of received signals varies with respect to the rail surface characteristics, spotting the reflection from a defect can be extremely challenging. These signals are in general contaminated with noise and have low repeatability that could hinder the proper identification of the defect signal. In view of this, an innovative signal processing technique called a self-adaptive-smart algorithm (SASA) was designed and developed. In SASA, the incident wave that is the first coming wave-packet is taken as a mother wavelet. A library of possible mother wavelets was designed based on the experimental data. As the incident wave for each sensing point varies because of the physical condition of the rail surface and the laser excitation, the algorithm automatically picks the mother wavelet from the library that generates the largest absolute cross-correlation with the incident wave. SASA is found to be able to suppress the unwanted wave packets from the overall signal leaving behind only the incident wave for a healthy specimen, and the incident wave and its reflection from the defect for a damaged specimen. The functioning of the algorithm was successfully tested by carrying out extensive experiments on a real rail track in the presence of different types of surface and sub-surface defects on its head and web. The obtained results prove the effectiveness of using SASA in localizing defects in rails with a marginal error. Notably, the proposed method has benefits such as being self-adaptive, can help suppress high levels of noise, bring the peak of defect reflected wave in the center, and distinguish between a healthy and damaged sample.
关键词： Structural integrity,Subsurface defects,Signal processing,Rail track,Rayleigh wave,Laser system
更新于2025-09-23 15:21:01
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Reference Module in Materials Science and Materials Engineering || Super Resolution Fluorescence Microscopy
摘要： Superresolution in microscopy has intrigued researchers for many years. There is always a challenge in overcoming what seems to be a fundamental limit. Even since the award of the Nobel prize in Chemistry in 2014 for stimulated emission depletion (STED) microscopy and localization microscopy, there has been continuing activity to improve these techniques, by reducing specimen radiation exposure for example. The term superresolution refers to overcoming the classical limit to resolution, usually defined in terms of either the Abbe resolution limit, or the Rayleigh two-point resolution criterion. These two measures are robust, the Abbe limit in particular providing a hard limit that can only be beaten by a fundamentally new approach, almost like a ‘trick’. Rayleigh recognized that his criterion was arbitrary, but considered it robust enough. Originally defined for incoherent imaging of self-luminous objects, its applicability has been extended to coherent and partially coherent systems, and later to confocal microscopy and other developments. This is usually achieved by the so-called ‘generalized Rayleigh resolution criterion’, according to which two points are taken as being just resolved when the intensity of the image midway between the points is 0.735 times that at the points themselves. It is found that around this value the image contrast changes quickly for a small change in the separation of the points.
关键词： Abbe resolution limit,Rayleigh criterion,Localization microscopy,STED,Superresolution,Microscopy
更新于2025-09-23 15:21:01
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Simple direct observation of polarization changes of Rayleigh scattering on sugar solution at low concentration
摘要： The direct measurement of polarization changes can be used to prove Rayleigh scattering at low concentration of sucrose and commercial sugar solution. The polarization changes of scattered light is linearly dependent on the polarization angle in the range 0° to 70°, and linearly dependent on sample concentration (number of particles). This method is able to show sugar’s relative different quality, i.e. pure sucrose and commercial sugar due to different molecular size and additional impurities in the commercial sugar.The method is simpler and easier to study the interaction of light with matter for special condition. Additionally, for other known parameters, the method can be developed to obtain the molecular size and composition information of the sample using Rayleigh scattering.
关键词： direct polarization changes,Rayleigh scattering,Sugar solution
更新于2025-09-23 15:21:01
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Diagnostics of polarization purity of x rays by means of Rayleigh scattering
摘要： Synchrotron radiation is commonly known to be completely linearly polarized when observed in the orbital plane of the synchrotron motion. Under actual experimental conditions, however, the degree of polarization of the synchrotron radiation may be lower than the ideal 100%. We demonstrate that even tiny impurities of polarization of the incident radiation can drastically affect the polarization of the elastically scattered light. We propose to use this effect as a precision tool for the diagnostics of the polarization purity of the synchrotron radiation. Two variants of the diagnostics method are proposed. The ?rst one is based on the polarization measurements of the scattered radiation and relies on theoretical calculations of the transition amplitudes. The second one involves simultaneous measurements of the polarization and the cross sections of the scattered radiation and is independent of theoretical amplitudes.
关键词： polarization purity,diagnostics,Rayleigh scattering,x rays,synchrotron radiation
更新于2025-09-23 15:21:01
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Lattice effect in Mie-resonant dielectric nanoparticle array under oblique light incidence
摘要： Ultra-thin optical structures, known as metasurfaces, have shown promising light controlling capability at the nanoscale. In this paper, we study their particular case, a periodic array of high-refractive-index nanoparticles with electric and magnetic resonances. The main result of the work is a numerical demonstration that the lattice effect in the periodic arrangement of nanoparticles changes the resonance position even if the resonances are above the diffraction wavelength (Rayleigh anomaly). We show that the disk resonance changes can be achieved not only by varying periods of the array under normal light incidence but also by changing the incident angle.
关键词： metasurfaces,Rayleigh anomaly,electric and magnetic resonances,high-refractive-index nanoparticles,lattice effect
更新于2025-09-23 15:21:01
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Relaxor Behavior in Ordered Lead Magnesium Niobate (PbMg <sub/>1/3</sub> Nb <sub/>2/3</sub> O <sub/>3</sub> ) Thin Films
摘要： The local compositional heterogeneity associated with the short-range ordering of Mg and Nb in PbMg1/3Nb2/3O3 (PMN) is correlated with its characteristic relaxor ferroelectric behavior. Fully ordered PMN is not prepared as a bulk material. This work examines the relaxor behavior in PMN thin films grown at temperatures below 1073 K by artificially reducing the degree of disorder via synthesis of heterostructures with alternate layers of Pb(Mg2/3Nb1/3)O3 and PbNbO3, as suggested by the random-site model. 100 nm thick, phase-pure films are grown epitaxially on (111) SrTiO3 substrates using alternate target timed pulsed-laser deposition of Pb(Mg2/3Nb1/3)O3 and PbNbO3 targets with 20% excess Pb. Selected area electron diffraction confirms the emergence of (1/2, 1/2, 1/2) superlattice spots with randomly distributed ordered domains as large as ≈150 nm. These heterostructures exhibit a dielectric constant of 800, loss tangents of ≈0.03 and 2× remanent polarization of ≈11 μC cm?2 at room temperature. Polarization–electric field hysteresis loops, Rayleigh data, and optical second-harmonic generation measurements are consistent with the development of ferroelectric domains below 140 K. Temperature-dependent permittivity measurements demonstrate reduced frequency dispersion compared to short range ordered PMN films. This work suggests a continuum between normal and relaxor ferroelectric behavior in the engineered PMN thin films.
关键词： random site model,relaxor,ferroelectricity,short- and long-range order,temperature-dependent Rayleigh analysis
更新于2025-09-23 15:21:01
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[IEEE 2019 IEEE 46th Photovoltaic Specialists Conference (PVSC) - Chicago, IL, USA (2019.6.16-2019.6.21)] 2019 IEEE 46th Photovoltaic Specialists Conference (PVSC) - Assessing the impact of back-contact recombination on CIGS solar cells with improved crystal quality
摘要： We propose and prove a theorem that allows the calculation of a class of functionals on Poisson point processes that have the form of expected values of sum–products of functions. In proving the theorem, we present a variant of the Campbell–Mecke theorem from stochastic geometry. We proceed to apply our result in the calculation of expected values involving interference in wireless Poisson networks. Based on this, we derive outage probabilities for transmissions in a Poisson network with Nakagami fading. Our results extend the stochastic geometry toolbox used for the mathematical analysis of interference-limited wireless networks.
关键词： interference,Wireless networks,time diversity,correlation,Poisson point process,Nakagami fading,stochastic geometry,Rayleigh fading
更新于2025-09-23 15:19:57