the specular reflectance of ir-opaque coatings

A reflecting-layer model of the specular reflectance of a rough, thick, absorbing, dielectric film has been developed and fitted to the spectra of seven optical-black coatings between 12 and 300 m. The coatings were quite different. At 100 m their reflectance varied by a factor of nearly 10³. The model determines optical constants and surface parameters, and indicates which parameters control reflectance in the far IR.     

Role of specular reflection of electrons in the radio frequency surface magneto impedance of metals

The effect of a parallel magnetic field on the 10-mHz surface resistance of gallium single crystals is reported. We suggest that the observed structure can be interpreted in terms of an angular dependence of the probability of specular reflection of the electron at the crystal surface. This model allows a quantitative determination from the data of the temperature-dependent electron mean free path for electron wave vectors with a narrow range that is determined by the magnetic field and crystal orientation.     

Determination of the mean energy of backscattered electrons in dependence on the exit angle

A semiconductor detector was used to measure the mean energy of backscattered electrons as a function of the exit angle. New regularities of electron backscattering were found. A nonmonotonic dependence of the mean energy of backscattered electrons on the exit angle and the primary electron energy for materials with different atomic numbers was revealed.     

The dependence of sputtering efficiency on ion energy and angle of incidence

Abstract

Earlier measurements of sputtering efficiency of polycrystalline targets (fraction of impinging ion energy leaving the target through sputtering and backscattering) have been extended to higher energies. Lead and copper targets were bombarded with several different projectiles with energies between 80 and 1200 keV. The sputtering efficiency decreases with increasing energy. This decrease is ascribed to the combined influence of changes in the scattering cross section with energy, and to electronic stopping. The results may be described as a function of the mass ratio M ₂/M ₁ and the reduced energy ? only.

The sputtering efficiency was measured as a function of angle of incidence of the bombarding ions. To ensure complete collection of sputtered and backscattered particles, it was possible to cover only the region of incidence angle from 0° to 45°. Targets of copper, silver, and lead were investigated with 17 different ion-target combinations. The sputtering efficiency increased with angle of incidence. This increase is described well by a simple interpolation formula by Sigmund.     

Fast algebra algorithm of shape-from-shading with specular reflectance

Shape-from-shading (SFS) is to reconstruct three-dimensional (3D) shape from a single gray image, which is an important problem in computer vision. We propose a novel SFS method based on hybrid reflection model which contains both diffuse reflectance and specular reflectance. The intensity gradient of image is in the direction that the shape of urface changes most, so we use directional derivative of the reflectance map as parts of objective function. When discrete characteristic of digital images is considered, finite difference approximates differential operator. So the reflectance map equation described by a partial differential equation (PDE) turns into an algebra equation about the nknown surface height correspondingly. Using iterative numeric computation, a new SFS method is gained. Experiments on synthesis and real images show that the proposed SFS method is accurate and fast.     

The dependence of the uniaxial magnetic anisotropy in evaporated films on the angle of incidence

The method of local ferromagnetic resonance and direct torsional measurements were used to measure the dependence of the magnetic anisotropy in permalloy films on the angle of incidence in a broad range of such angles. It was found that this dependence is not monotonous and that at larger angles of incidence the easy axis of magnetization is rotated. An interpretation of this phenomenon is proposed.

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In conclusion the authors wish to thank J. Grolmus for performing some of the measurements, members of the mechanics workshop of the Institute of Physics, Czechoslovak Academy of Sciences, for carefully preparing the apparatus, and particularly K. Schaffner for accurately making the resonance cavity. We thank J. Kaczér and V. Janovec for carefully reading this paper and for a number of valuable remarks.     

Sxaps spectra of pyrolytic graphite as a function of the angle of incidence of the incoming electrons

Soft X-ray appearance potential (SXAPS) spectra of pyrolytic graphite as a function of the angle of incidence of the incoming electrons have been measured to obtain information about surface plasmon excitation. Plasmons can be coupled with a core hole and two slow electrons above the Fermi level or with a fast incoming electron. In the last case angular dependent plasmon excitation can be observed. Coupling with the fast incoming electron is observed, but band structure effects cannot be neglected to explain the observed structure. Measurements were performed on clean and hydrogen-contaminated pyrolytic graphite. A signal increase over the whole spectrum was observed after hydrogen contamination, probably due to a rearrangement of the surface lattice structure. Bombardment of the surface with electrons of 2 keV gave a decrease in spectral intensity probably due to surface damage.     

Small angle scattering of electrons

The small angle scattering of low energy electrons has been studied. It has been shown that the cross-sections obtained using the Born's first approximation, corrected for screening effects should be used to study the small angle scattering of low energy electrons.     

Effect of oblique incidence angle of sunlight on the optimized folding angle of V-shaped organic solar cells

We numerically investigate the effect of the incidence angle of sunlight on the optimized folding angle of V-shaped organic solar cells (VOSCs) to obtain the best power conversion efficiency in a realistically operating environment. The light absorbance at the active layer is calculated based on the finite element method with respect to the incidence angle of sunlight and the folding angle of the VOSC. We calculate the generation energy density per day at each folding angle by integrating the angular response of the short-circuit current and the open-circuit voltage with the consideration of the variation of the incidence angle during daytime. We show that the optimized folding angle of the VOSC based on the variation of the generation energy density per day is close to that determined from the variation of the electric power density in normal incidence, which has been widely used to optimize the folding angle of VOSCs.     

探测激光入射角对猫眼效应反射特性的影响

光电装备的光学窗口对入射激光有较强的反射特性,即猫眼效应现象。为了研究利用猫眼效应来进行主动探测的适用条件,弄清探测激光入射角对猫眼效应反射特性的影响,建立了斜入射猫眼效应反射模型,分析并仿真了探测激光在目标系统处的入射角不同的情况下的后向反射激光特性,以及探测系统所能够接收的原路返回激光的远场能量分布情况。结果表明：对于特定的目标系统,猫眼效应现象只存在于一定的探测激光入射角范围之内,在此范围之内,猫眼效应反射特性与探测激光的入射角关系密切;基于猫眼效应的激光主动探测、定位等应用也是可行的。     

探测激光入射角对猫眼效应反射特性的影响

 光电装备的光学窗口对入射激光有较强的反射特性,即猫眼效应现象。为了研究利用猫眼效应来进行主动探测的适用条件,弄清探测激光入射角对猫眼效应反射特性的影响,建立了斜入射猫眼效应反射模型,分析并仿真了探测激光在目标系统处的入射角不同的情况下的后向反射激光特性,以及探测系统所能够接收的原路返回激光的远场能量分布情况。结果表明：对于特定的目标系统,猫眼效应现象只存在于一定的探测激光入射角范围之内,在此范围之内,猫眼效应反射特性与探测激光的入射角关系密切;基于猫眼效应的激光主动探测、定位等应用也是可行的。     

激光入射角对靶面方向超热电子发射的影响

实验研究了超短超强激光脉冲与薄膜靶相互作用中产生的超热电子角分布随激光入射角的变化.在靶面方向观测到一束方向性很好的高能超热电子.该高能超热电子束的电子数目随着激光入射角的增大而增大.对结果的分析表明，表面准静态磁场是导致表面电子产生的主要原因. 关键词： 超热电子 表面准静态磁场 超强激光脉冲与等离子体相互作用     

Effect of laser beam incidence angle on the thermoelastic generation in semi-transparent materials

When a laser beam is absorbed in a semi-transparent material, a volume acoustic source is created owing to penetration of the laser beam inside the material and to thermoelastic transduction. Many experimental and theoretical studies have been conducted to better understand this ultrasound generation process with normal laser light incidence on the material surface. The purpose of this paper is to analyze the effects of the asymmetry caused by oblique incidence of a laser line source on the generation of acoustic waves in semi-transparent isotropic materials. Experiments on a glass plate demonstrate that such an obliquely incident laser light strongly affects bulk acoustic waves generation. Compressional and shear waves are enhanced and the loss of symmetry of the acoustic source causes asymmetrical behavior of the acoustic waves. Surprisingly, compressional-wave amplitude decreases whereas shear-wave amplitude increases in the region where the electromagnetic energy is refracted. This feature is explained by semi-analytical calculations.     

Studies of the electrical double layer and of adsorbed species on electrodes using modulated specular reflectance spectroscopy

The optical properties of adsorbed hydrogen on a platinum cathode have been studied. The results are interpreted in terms of r and s-adatom formation for the two types of adsorption. The reflectivity change in the double layer region of potential is ascribed to an electroreflectance contribution from the metal. Studies of the simple double layer formed between KF solution and a lead or mercury electrode show that the reflectivity changes caused by the diffuse double layer are small compared with contributions from the compressed water in the inner layer and from the electroreflectance effect.     

Effect of angle of incidence on self-mixing laser Doppler velocimeter and optimization of the system

Based on the theory of speckle and self-mixing interference in laser-diode, three-facet cavity model is introduced to analyze laser Doppler effect based on self-mixing interference in the case of a rough surface, and numerical solution of the signal is obtained. Simulation results of speckle-modulated Doppler signal based on self-mixing effect and tracking accuracy at different incident angles are given using parameters employed in the experiment. Simulation results indicate incident angle of around 30° is most suitable when both tracking accuracy and signal amplitude are considered. Experimental waveforms agree well with simulation results, and similar conclusions as simulation predictions about changing trend of tracking accuracies of the system at different incident angles can be made. Combining with difference frequency analog phase-lock loop (PLL) technique and appropriate sampling time, a laser Doppler velocimeter with tracking accuracy better than 1.3% in the range of 10-470 mm/s is realized.     

Polarization dependence of the spontaneous radiation of hot electrons

This paper reports on the results of investigations into the polarization dependence of the spontaneous radiation of hot electrons due to their intervalley redistribution in multivalley semiconductors. It is demonstrated that the radiation is predominantly polarized normally to the electric field and the direction of polarization and its intensity can vary according to the degree of electron redistribution, the electron concentration, and the heating electric field.     

The probable angle of incidence of ions onto the first wall of a fusion device in dependence on the magnetic field inclination

Modelling results on the effect of the magnetic field inclination on angles of incidence of plasma ions onto a first wall surface of a magnetically confined plasma device are presented. Different periphery plasma parameters are considered. Emission areas in plasma for ions impinging the surface at a given observation point are found.     

A direct indication for specular reflection of conduction electrons at the vacuum boundary of metal films

Highly disordered films of Al, Cu, Ag and Au are deposited at low temperatures on top of an annealed layer of the same metal. Although two electric conductors are connected in parallel, the total conductance of the sandwich first decreases, then passes through a minimum, and finally increases with increasing thickness of the disordered overlayer. Such curves of the total conductance versus thickness of the second film are interpreted within the Fuchs-Sondheimer model of the geometrical size effect. This model is used to calculate the fraction of specularly scattered conduction electrons at the uncovered surface, and the mean free path of the conduction electrons in the quench condensed overlayer.     

胶质红外量子点薄膜入射角对荧光特性的影响分析

胶质红外量子点优异的光学性能使其荧光特性具有广泛的应用前景,在实际应用中通常需要封装成薄膜形态以保持稳定的荧光特性。然而,分散形式的改变可能会导致量子点荧光效率降低以及荧光角度特性变化。因此,建立了红外量子点荧光强度探测系统,对胶质红外量子点薄膜在不同角度激发光入射时产生的荧光分布情况进行研究。实验及分析结果表明,激发光与样品表面夹角大小在10°～170°之间的较大范围内入射时,在反射及透射荧光区域均可探测到荧光峰值强度70%～80%以上的荧光出射,在这一范围内的反射荧光与透射荧光强度差异和荧光强度随激发光入射角度的变化规律分别与样品中量子点的浓度以及分布形态有关。同时,随着入射激光能量的增强,样品出射荧光强度对于入射角度变化的“平坦”范围进一步扩大。