Analysis of skin surface roughness by visual assessment and surface measurement

In this study, we analyze the surface roughness of human skin using human visual assessment and statistical features of three-dimensional shape data and goniometric reflectance data. We use eight skin replicas taken from the cheeks of women. First, we perform human visual assessment to obtain the roughness rankings. Second, we measure three roughness parameters by currently used methods. These parameters show no significant correlation with the roughness rankings. Third, we measure the skin surface shape to calculate surface normal vectors. We show that the surface normal distribution of the skin is isotropic and Gaussian, and the standard deviation has a good correlation with the roughness rankings. Finally, we analyze the goniometric reflectance data to approximate the surface reflection using the Oren-Nayar model. We find that the standard deviation estimated using this model corresponds to the roughness rankings. Thus, this parameter can be effectively used for describing skin roughness.     

The effect of surface roughness on thermal-elasto-hydrodynamic model of contact mechanical seals

In this paper,the effect of surface roughness on sealing clearance,pressure distribution,friction torque and leakage is studied by the thermal-elasto-hydrodynamic mixed lubrication model.A convergent nominal clearance is formed by the pressure deformation and thermal deformation of the seal faces.This causes more serious wear in the inner side than that of the outer side of the contact area.Mass leakage increases with the growing of the surface roughness.The temperature and thermal deformation on the seal surface increases substantially if the roughness is reduced.The contact mechanical seals have consistent performance when the standard deviation of surface roughness is approximately 0.2μm.In order to validate the theoretical analysis model,a method combining the measurement of three-dimensioned profile and Raman spectrum is proposed.     

Laser cutting of polymeric materials: An experimental investigation

The CO₂ laser cutting of three polymeric materials namely polypropylene (PP), polycarbonate (PC) and polymethyl methacrylate (PMMA) is investigated with the aim of evaluating the effect of the main input laser cutting parameters (laser power, cutting speed and compressed air pressure) on laser cutting quality of the different polymers and developing model equations relating input process parameters with the output. The output quality characteristics examined were heat affected zone (HAZ), surface roughness and dimensional accuracy. Twelve sets of tests were carried out for each of the polymer based on the central composite design. Predictive models have been developed by response surface methodology (RSM). First-order response models for HAZ and surface roughness were presented and their adequacy was tested by analysis of variance (ANOVA). It was found that the response is well modeled by a linear function of the input parameters. Response surface contours of HAZ and surface roughness were generated. Mathematical model equations have been presented that estimate HAZ and surface roughness for various input laser cutting parameters. Dimensional accuracies of laser cutting on polymers were examined by dimensional deviation of the actual value from the nominal value. From the analysis, it has been observed that PMMA has less HAZ, followed by PC and PP. For surface roughness, PMMA has better cut edge surface quality than PP and PC. The response models developed can be used for practical purposes by the manufacturing industry. However, all three polymeric materials showed similar diameter errors tendency in spite of different material properties.     

Determination of the standard deviation of height on a rough surface using interference microscopy

When a rough surface is viewed in an interference microscope with tilt fringes introduced, the effect of the roughness is to reduce the average visibility of the tilt fringes. The relationship between the standard deviation of surface height and the average visibility of the tilt fringes is derived, and experimental results are presented of measurements made on ground glass surfaces using a Linnik interference microscope.     

Micromechanical model of deformation-induced surface roughening in polycrystalline materials

A micromechanical model has been developed to describe deformation-induced surface roughening in polycrystalline materials. The three-dimensional polycrystalline structure is taken into account in an explicit form with regard to the crystallographic orientation of grains to simulate the micro- and mesoscale deformation processes. Constitutive relations for describing the grain response are derived on the basis of crystal plasticity theory that accounts for the anisotropy of elastic-plastic properties governed by the crystal lattice structure. The micromechanical model is used to numerically study surface roughening in microvolumes of polycrystalline aluminum and titanium under uniaxial tensile deformation. Two characteristic roughness scales are distinguished in the both cases. At the microscale, normal displacements relative to the free surface are caused by the formation of dislocation steps in grains emerging on the surface and by the displacement of neighboring grains relative to each other. Microscale roughness is more pronounced in titanium, which is due to the high level of elastic-plastic anisotropy typical of hcp crystals. The mesoscale roughness includes undulations and cluster structures formed with the involvement of groups of grains. The roughness is quantitatively evaluated using a dimensionless parameter, called the degree of roughness, which reflects the degree of surface shape deviation from a plane. An exponential dependence of the roughness degree on the strain degree is obtained.     

Roughness reduction in submicron waveguides by low-molecular weight development

Roughness reduction of a submicron waveguide profile in chemically amplified negative resist is here performed by proper selection of an alkali-based developer, taking into account that its smaller molecules lead to smoother resist surface by altering the developing mechanism of aggregate extraction performed with standard quaternary ammonium hydroxide. Roughness is then analyzed by means of classical Atomic Force Microscope inspection; furthermore, a non-invasive line edge roughness analysis approach based on top-down scanning electron microscope acquisition gives comparable results, in terms of standard deviation and molecular aggregate periodicity.     

Electromagnetic field distribution on a rough gold thin film: An experimental study as a function of the gold thickness

The electromagnetic field distribution on an illuminated rough gold surface has been investigated by apertureless scanning near-field optical microscopy. The sample consists of an alumina substrate with a variable gold coverage ranging from 0 to 30 monolayers (ML). For such small thicknesses, the metal layer is not continuous but exhibits a certain roughness. We have studied the influence of this thickness on the electromagnetic field localization on the surface. For a gold coverage smaller than 10 equivalent monolayers, the electromagnetic field is almost uniform on the surface. For 10 and 14 ML, the field becomes inhomogeneous and isolated, localized peaks start to be visible. The width of the peaks is smaller than 50 nm. Above 14 ML, strong variations are apparent everywhere on the sample. Their amplitude tends to saturate beyond 24 ML. A complete statistical study of the sample (standard deviation, Fourier analysis) is performed.     

Additional Nonreciprocity Effects in the Magneto-Optics of Asymmetric Layer Structures

The structure of the adsorbed layer of alkali ions on the surface of colloidal silica solutions with a particle size of 27 nm has been studied by reflectometry and diffuse scattering of synchrotron radiation with a photon energy of about 71 keV. Electron density profiles in the direction perpendicular to the surface have been reconstructed from experimental data and spectra of the correlation function of heights in the surface plane have been obtained. The revealed deviation of the integral and frequency characteristics of the roughness spectra of the silica sol surface from predictions of the capillary-wave theory is of a fundamental character. This deviation is due to the contribution from roughnesses with low spatial frequencies ν < 10^?4 nm^–1 and to the interference of diffuse scattering from different layer interfaces of the surface structure.     

On the melting of gold nanoclusters formed by pulsed laser deposition on different substrates

The experimental results are presented for the backscattering of 500-eV electrons on Au nanoclusters formed on the surface of highly oriented pyrolytic graphite HOPG(0001) and amorphous SiO₂. It has been found that the measured intensity of the elastically backscattered electrons nonmonotonically depends on the size of nanoclusters. It has been shown that the observed features can be explained by an increase in the rms deviation of the atoms of the Au nanocluster with a decrease in its size. The difference in the dependence of the rms deviation of atoms on the size of the nanoclusters formed on the surfaces of HOPG(0001) and amorphous SiO₂ is qualitatively explained by an increase in the roughness of the nanocluster surface accompanying their formation under the strongly nonequilibrium conditions of pulsed laser deposition.     

Direct measurement of sidewall roughness of polymeric optical waveguides

Sidewall roughness (SWR) of fluorinated polyether waveguides fabricated using reactive ion etching in pure oxygen gas was directly measured using atomic force microscopy (AFM). We confirm that SWR is not the replicate of line edge roughness (LER) of the waveguides. Statistical information such as standard deviation of roughness, autocovariance function (ACF), and autocorrelation length (ACL) have been obtained from AFM measurements. The ACL varies in the similar manner as SWR along the depth of the waveguide, and both are dependent on the etch depth. The depth dependence can be explained by the change in the arrival dynamics of etchant ions in a mechanism involving both shadowing and first-order reemission effects.     

Dynamic fracture of the surface of an aluminum alloy under conditions of high-speed erosion

The kinetics of fracture and deformation of the standard aluminum alloy AD1 and a similar alloy subjected to severe plastic deformation by high-pressure torsion under conditions of high-speed erosion has been investigated. It has been shown that, with an increase in the loading rate, the fraction of the brittle component on the fracture surface of the standard material, as well as the thickness of the damaged layer, increases more significantly than that for the material after the severe plastic deformation by high-pressure torsion. A relationship of the surface roughness of the material after the erosion with the loading rate and the thickness of the erosion-damaged layer has been established.     

Talbot effect in metallic gratings under Gaussian illumination

Metallic gratings can be found in applications such as optical metrology. Due to their fabrication process, the surface presents a certain roughness. In this work, the effect of roughness on Talbot effect has been analyzed when the grating is illuminated with a Gaussian beam. A model based on Fresnel regime is used in order to determine the intensity distribution in the near field. Contrast of the self-images is obtained and it is found that it decreases in terms of the distance between the grating and the observation plane. When the autocorrelation function of roughness presents a Gaussian behaviour, the diffracted beams are still Gaussian although some of their properties change. For example, the width of the diffracted beams increases with respect to the case of the standard chrome on glass gratings. On the other hand, the power of each diffracted beam is independent on the roughness properties of the surface.     

不同电流下气体开关电极烧蚀特性实验研究

在不同短路电流条件下,进行了不锈钢(1Cr18Ni9Ti)电极气体火花开关连续多次自击穿放电实验,通过测量电极质量损失、表面粗糙度和自击穿电压的变化,研究电极烧蚀特性及其对自击穿性能的影响。实验结果表明:随着放电电流峰值和周期增大,电极材料烧损速率与电容电荷量呈线性增加,而电极表面烧蚀粗糙度与电流峰值呈线性增大,自击穿电压变化达到峰值和稳定区的放电次数减少,但稳定阶段的自击穿电压值及其相对标准偏差同时减少,五种放电电流情况下,自击穿电压概率密度分布均遵循高斯函数。     

表面粗糙度干涉图像处理中的阈值优选

提出用于表面粗糙度自动干涉法测量过程中的一种有效的白光干涉图像阈值分割方法，分割后的二值图像经过干涉条纹边界线萃取后得到的被测表面输廓波形和表面粗糙度参数的计算结果与高精度ＴＡＬＹＳＵＲＦ６型表面粗糙度测量仪的测量结果十分吻合，此种图像分割方法同样也适用于粗糙表面激光干涉图像的二值化分割。     

Whole field surface roughness measurement by laser speckle correlation technique

This paper describes a speckle correlation technique for the determination of surface roughness, ranging from 1.6 to 50 μm. Instead of moving the laser beam, the specimen is rotated to achieve angular speckle correlation (ASC) in the far-field plane. The technique is simple and requires minimum optical alignment. The experimental results show a good agreement with the standard specimen of known roughness. An error analysis on the experiment has been carried out. Together with the theoretical curves, the roughness values can be easily related to the change of incidence angle at a particular visibility of the correlation fringes between two speckle patterns.     

基于LIBS煤中碳元素定量分析研究

详细介绍利用激光诱导击穿光谱(laser-induced breakdown spectroscopy,LIBS)进行煤中碳(C)元素含量定量分析的技术和手段。通过对光谱数据进行积分、归一化、筛选等处理,克服了由于激光源能量起伏、自吸收及样品表面粗糙度等因素引起分析精度差的缺点。该方法已应用到激光煤质在线分析仪中并取得了满意的分析结果,对煤粉中C元素含量分析的标准偏差不大于1.6%,其方法同样可用于煤中其他元素的分析。     

Nickel-chromium interface resolution in Auger depth profiles

Auger depth resolutions for fine-grained crystalline Ni/Cr multilayers have been determined. Resolution is shown to be a function of ion species, ion energy, ion incident angle, and the presence of reactive species. Deterioration of interface resolution with depth is shown to be the result of cumulative surface roughness induced by the ion beam to an extent proportional to the ion velocity normal to the surface. The presence of a reactive species to create an amorphous surface layer is shown to inhibit the development of surface roughness. The best resolution was obtained using low energy Xe ions and large ion beam angles. The ultimate resolution is limited by the fabrication perfection of the standard, and not by the sputtering process or by the Auger mean free path length.     

光学轮廓仪对光学元件表面空间波长回应的研究

在分析光学轮廓仪的空间分辨率和带限功率谱密度函数的基础上，用新测不同要品的大量数据研究了光学元件表面粗糙度测量与光学轮廓仪对表面空间波长的带限顺应关系，对由光学轮廓仪不同带宽限制内测量元件表面粗糙度不同回应所引起的不同偏差的解决办法提出了几点建议。     

不同表面激光双向反射分布函数的实验研究

根据粗糙面电磁散射理论讨论了粗糙表面双向反射分布函数（ＢＲＤＦ）和单位面积激光雷达截面的关系。测量不同粗糙度金板、铝基、钢基和涂层样片在０．６３μｍ的双向反射分布函数。分析了高度起伏均方根δ，斜率起伏均方根ｓ，介电常数对双向反射分布函数的影响。最后，将部分粗糙样片的双向反射分布函数理论计算结果与实验数据比较，两者有良好的吻合。     

Surface studies of niobium chemically polished under conditions for superconducting radio frequency (SRF) cavity production

The performance of niobium superconducting radiofrequency (SRF) accelerator cavities is strongly impacted by the topmost several nanometers of the active (interior) surface, especially as influenced by the final surface conditioning treatments. We examined the effect of the most commonly employed treatment, buffered chemical polishing (BCP), on polycrystalline niobium sheet over a range of realistic solution flow rates using electron back scatter diffraction (EBSD), stylus profilometry, atomic force microscopy, laboratory XPS and synchrotron (variable photon energy) XPS, seeking to collect statistically significant datasets. We found that the predominant general surface orientation is (1 0 0), but others are also present and at the atomic-level details of surface plane orientation are more complex. The post-etch surface exhibits micron-scale roughness, whose extent does not change with treatment conditions. The outermost surface consists of a few-nm thick layer of niobium pentoxide, whose thickness increases with solution flow rate to a maximum of 1.3-1.4 times that resulting from static solution. The standard deviation of the roughness measurements is ±30% and that of the surface composition is ±5%.