Parametric ergodicity to measure roughness from a single sample

We introduce a concrete random model system to study the concept of parametric ergodicity. It consists of a continuum mechanical cavity with an embedded random mass distribution, constrained by a parametrized boundary condition. The interest is twofold. On one hand, there is the practical interest of obtaining ensemble averages of physical quantities from a small number of experimentally available samples, in many cases only one. This is typically the case in studies on conductance fluctuations through disorder mesosocopic systems. On the other hand we want to develop more insight into the meaning of parametric ergodicity. For this, we focus on the statistical distribution of resonant frequency generated by the ensemble of random samples, and how to produce the same distribution from a single sample subject to changing a boundary condition — the external parameter. The paper shows how the changing of the boundary condition is equivalent to scanning the ensemble of equivalent samples.     

A proposed experiment to measure surface roughness in Si/SiO2 system

The adsorption of oxygen on clean cleaved (111) silicon surfaces has been investigated by high resolution electron spectroscopy (HRES), Auger electron spectroscopy (AES) and ellipsometry. Localized vibrations ($\text{h}\text{?}\text{ω = 94}$, 130 and 175 meV) which are related to the binding state band of oxygen are identified with HRES. AES measures the concentration of adsorbed atoms basically independent of their binding state while ellipsometry refers additionally to the optical properties of the adsorbed layer. The same adsorption kinetics was found with the three methods. Oxygen therefore adsorbs in a single likely molecular state. The sticking coefficient S increases exponentially with the surface step concentration. S is also enhanced by the presence of nude ion gauges. Depending on these parameters sticking coefficients between 2 × 10^?4 and 10^?1 have been obtained. This result might contribute to an explanation of the large differences in earlier works.     

Relation for estimating the reflectance of a very rough surface with an approximately one-dimensional distribution of roughness

A relation for estimating the reflectance of a very rough surface with an approximately one-dimensional distribution of roughness is derived for the case of normal incidence and reflection in the specular direction within the solid diffraction angle. The reflectance values are determined both experimentally and by calculation using the derived relation for two approximately one-dimensional rough steel samples with rms roughnesses of 0.5 and 1.3 μm for a wavelength of 0.6328 μm. The resulting values are found to agree satisfactorily with each other.     

Optical sensor to measure the velocity of a surface

A device for measuring the velocity of a surface using the transit time technique is presented. The design of the prototype has been developed particularly for automotive use. Moreover, this paper gives a thorough evaluation of the problem of data elaboration.     

Study of photons reflection on rough surface

The purpose of this paper is to study the probability distribution of photon reflection on rough surface experimentally and theoretically. We showed experimentally that for photon reflection on rough surface, the distribution was characterized by the ratio τ/σ, which was defined as the “correlation roughness” of the reflecting surface. Quantitative experimental results based on single-photon counter are compared to the Monte Carlo simulation results. At last, how the intensity of low light-level can be retrieved from photon counting results using improved models is shown.     

Study of light collection as a function of scintillator surface roughness

The variation of pulse-height spectra was observed under the consecutive treatment of CsI:Tl plane scintillators by different abrasives – with increase of the abrasive grain size the double peaks of the total absorption transferred into the single peaks with acceptable resolution. The light collection simulation of the differently treated surfaces was performed to interpret the experimental results. In simulation the surface relief was represented as a set of micro-facets with slope distribution functions extracted from the experimentally measured reflectance distribution functions. The behavior of the simulated pulse-height spectra in the vicinity of the total absorption peak under the assumption of uniform scintillation distribution in the scintillator volume was in a good agreement with experimental results for different surface treatment conditions. From pulse-height spectrum simulations for different positions of the point light source it was determined that the double peaks in experimental and simulated spectra had been caused by the scintillations in different scintillator areas. The decrease of the light output and the resolution improvement occurred under the input surface treatment of the plane scintillator by the larger abrasive was caused by the increase of the average pass length of light to the output detector window and by the decrease of the difference of this value for the various scintillator areas, respectively.     

Use of the speckle effect to analyze vibrations of a rough surface

An analysis is made of a contactless method of recording the vibrations of a rough surface using the speckle effect. Dependences of the percent modulation of the photodetector electric signal on the vibration amplitude and the parameters of the optical system are given and this optical dependence is checked experimentally. Results of a spectral analysis of the vibrations of an electric motor casing are presented for illustration purposes. It is noted that this method may be used to study vibrations of heated surfaces and transparent media. Zh. Tekh. Fiz. 67, 71–75 (August 1997)     

Quasi-steady-state surface acoustic waves at a rough solid surface

Sound propagation along an inhomogeneous solid-vacuum interface is considered. The frequency-wavenumber relation has been obtained for the transverse-polarized surface wave and the range of existence of this wave has been analyzed. The surface roughness is shown to produce additional damping.     

Width of steps on a rough surface

Computer simulation of a rough surface indicates that a relation exists between the experimentally determined degree of roughness of interlayer boundaries and the correlation length, on the one hand, and the characteristic width of atomic steps on the layer interfaces in multilayered structures, on the other hand.     

二氧化钛薄膜表面粗糙度研究

为了探究二氧化钛(TiO₂)薄膜表面粗糙度的影响因素, 利用离子束辅助沉积电子束热蒸发技术对不同基底粗糙度以及相同基底粗糙度的K9玻璃完成二氧化钛(TiO₂)光学薄膜的沉积。采用TalySurf CCI非接触式表面轮廓仪分别对镀制前基底表面粗糙度和镀制后薄膜表面粗糙度进行测量。实验表明, TiO₂薄膜表面粗糙度随着基底表面的增大而增大, 但始终小于基底表面粗糙度, 说明TiO₂薄膜具有平滑基地表面粗糙的作用; 随着沉积速率的增大, 薄膜表面粗糙度先降低后趋于平缓; 对于粗糙度为2 nm的基底, 离子束能量大小的改变影响不大, 薄膜表面粗糙度均在1.5 nm左右; 随着膜层厚度的增大, 薄膜表面粗糙度先下降后升高。     

Analysis of speckle images to assess surface roughness

Digital speckle images are photographed for different aluminum rough surfaces using a CCD camera. The obtained speckle images are fed to a PC and analyzed making use of the MATLAB program. The computerized binary images are investigated. The signal-to-noise ratio is computed from these numerical images. It is shown that the surface roughness of the examined surfaces is dependent upon the degree of agglomeration of the speckle images.     

Effect of the surface roughness on Bean-Livingston surface barrier

Bean-Livingston barrier for a single Abrikosov vortex interacting with the rough surface is calculated as a function of the random characteristics of the surface roughness. It has been shown that even a respectively smooth surface roughness results in an essential decrease of the Bean-Livingston surface barrier.     

X-ray scattering from a randomly rough surface

Abstract

On the basis of the method of reduced Rayleigh equations we present a simple and reciprocal theory of the coherent and incoherent scattering of x-rays from one- and two-dimensional randomly rough surfaces, that appears to be free from the limitations of earlier theories of such scattering based on the Born and distorted-wave Born approximations. In our approach, the reduced Rayleigh equation for the scattering amplitude(s) is solved perturbatively, with the small parameter of the theory η(ω) = 1 - ε(ω), where ε(ω) is the dielectric function of the scattering medium. The magnitude of η(ω) for x-rays is in the range from 10^?6 to 10^?3, depending on the wavelength of the x-rays. The contributions to the mean differential reflection coefficient from the coherent and incoherent components of the scattered x-rays are calculated through terms of second order in η(ω). The resulting expressions are valid to all orders in the surface profile function. The results for the incoherent scattering display a Yoneda peak when the scattering angle equals the critical angle for total internal reflection from the vacuum-scattering medium interface for a fixed angle of incidence, and when the angle of incidence equals the critical angle for total internal reflection for a fixed scattering angle. The approach used here may also be useful in theoretical studies of the scattering of electromagnetic waves from randomly rough dielectric-dielectric interfaces, when the difference between the dielectric constants on the two sides of the interface is small.     

Detection of a small defect on a rough surface

We report experimental results that show that the far-field correlation function is sensitive to a small local change in rough-surface geometry, where the speckle spatial correlation rather than the sample ensemble average is adopted. The angular cross-correlation function of the far-field speckles scattered by one-dimensional random rough surfaces is measured when a polarized beam of light is incident upon the rough surface from vacuum, where one part of the surface used is a thin dielectric film deposited upon a glass substrate and the other part is identical to the first except for a localized defect. We envisage application of this sensitivity property to inspection of a sample with a defect by means of speckle mapping.     

Poly-Gaussian models of a non-Gaussian randomly rough surface

Poly-Gaussian models are developed for non-Gaussian random processes, which make it possible to describe and imitate rough surfaces with various densities of roughness height distribution and correlation properties; the algorithms for numerical and analytical calculations of statistical characteristics of non-Gaussian reliefs are also worked out. Examples are given for the application of the integral poly-Gaussian model.