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Interferometric Angular Decorrelation Analysis of 1-D Rough Surface With Pencil Beam Incidence
摘要： Interferometric synthetic aperture radar (InSAR) uses phase difference of radar echoes, either from multiple passes along the same trajectory or from multiple displaced phase centers on a single pass, to generate interferogram. Scattering correlation in the angular dimension is a critical factor determining the quality of InSAR interferogram. It can be modeled with the angular correlation function (ACF). In this letter, the ACF of a 1-D rough surface under incidence of a tapered wave, namely, a pencil beam, is studied numerically for correlation analysis of InSAR. An analytic ACF is ?rst derived based on the ?rst-order small perturbation method. It is then validated statistically by the method of moment of electromagnetic scattering. Analysis of the ACF simulations indicate that the ACF of backscattering from a randomly rough surface exhibits a shape of sinc function, which depends on tapering parameter g, interferometric incidence angles θ1 and θ2. Several numerical simulations of different rough surface spectrums demonstrate that the analytical ACF ?ts well with numerical results as long as g is the larger several correlation lengths l.
关键词： interferometric synthetic aperture radar (InSAR),Angular correlation function (ACF),small perturbation method (SPM),surface roughness
更新于2025-09-09 09:28:46
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Materials Science and Technology of Optical Fabrication || Surface Roughness
摘要： Because it influences optical-scatter losses and downstream laser modulation [1], the surface roughness of an optical-glass component is an important parameter for many optical systems (including lasers and telescopes). During optical polishing, a number of interactions between the workpiece, polishing slurry, and pad may influence the resulting workpiece roughness at different spatial scale lengths. The phenomena affecting large spatial scale length (>1 mm) on the workpiece (i.e. surface figure) are described in Chapter 2 (see Figure 2.1). By contrast, in this chapter, the phenomena and process parameters affecting short spatial scale lengths (<1 mm) (i.e., surface roughness from AFM2 scale roughness to μ-roughness) are described (see Figure 1.8). Fine-scale roughness, typically measured by atomic force microscopy (AFM), is referred to as AFM1 (≤5 μm) and AFM2 roughness (≤50 μm), as represented on the right of the plot. Roughness at this scale is influenced by parameters such as the single-particle removal function, Beilby layer properties, slurry particle size distribution (PSD), pad topography, pad mechanical properties, and slurry particle redeposition. The next higher spatial scale length (the micrometer to millimeter range, known as micro- or μ-roughness), is usually measured by white-light interferometry (Figure 1.8). μ-Roughness is affected not only by the smaller spatial-scale length phenomena given above, but also by factors governing slurry-interface interactions, such as the spatial distribution of slurry particles present at the interface. These parameters and phenomena are listed Figure 4.1, consisting of a schematic of the workpiece–lap interface at the spatial scale length of interest that influences the final polished surface roughness. Figure 4.1 provides a valuable outline for this chapter.
关键词： Optical Polishing,Slurry PSD,Pad Topography,AFM,μ-Roughness,Surface Roughness
更新于2025-09-04 15:30:14
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Improved Retention Performance in Graphene-Ferroelectric Memory Device Through Mitigation of the Surface Roughness of the Ferroelectric Layer
摘要： A ferroelectric-gated graphene field-effect transistor was fabricated with a bottom-gate structure. A ferroelectric gate dielectric was formed using the spin-coating method. Two samples were made, one with a single coating and the other with a double coating. It was observed that the data retention times of the two samples were significantly different. When comparing the surface roughness, the surface of the thin film produced by the double coating was much flatter. Based on the observation of the surface morphology, an interfacial layer composed of air was deduced as the origin of both the depolarization and short retention time. That is, when fabricating the graphene-ferroelectric memory device, the importance of the interface treatment could be confirmed. Based on these results, it is expected that a much more reliable device can be realized through surface engineering via a graphene-ferroelectric device process.
关键词： Surface Roughness,Graphene,Ferroelectric,Interface
更新于2025-09-04 15:30:14
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[IEEE 2018 IEEE International Conference on Computational Electromagnetics (ICCEM) - Chengdu (2018.3.26-2018.3.28)] 2018 IEEE International Conference on Computational Electromagnetics (ICCEM) - Roughness Impact on the RCS of Simple Canonical Objects in the Terahertz Regime
摘要： The higher the frequency is, the greater the influence of the precision and the realism of the CAD models on electromagnetic (EM) scattering characteristics are. In the terahertz (THz) regime, surfaces of most objects can’t be taken as smooth according to Rayleigh criterion. The interaction of EM waves and the surface presents a coherent part in the specular direction and a scattering part in the other directions. Unfortunately, the roughness of surface can’t be represented by the CAD geometry. Based on statistics theory, the rough surface height profile is fully determined by the height probability density function (pdf) and its autocorrelation functions. Without loss of generality, the height pdf of surface is assumed to be Gaussian. Under the assumption, the random Gaussian rough is correspondingly generated. The original CAD surface geometry and the random Gaussian rough surface are superposed as the input of EM computation. To demonstrate the roughness impact on RCS, EM scattering characteristics of simple canonical objects such as plate and dihedral in the THz regime are investigated. Taking into account the statistical surface roughness, the ray-based high-frequency EM method, shooting and bouncing rays (SBR), is utilized to compute the RCS of the objects above in the THz regime. Furthermore, the inverse synthetic aperture radar (ISAR) images are also carried out via filtered back projection (FBP) method. The EM scattering characteristics of the objects above in the THz regime are analyzed. Great differences of the objects EM scattering characteristics between the smooth and rough ones are observed and discussed.
关键词： roughness,shooting and bouncing rays,terahertz (THz),canonical objects
更新于2025-09-04 15:30:14
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Annual dynamics of shortwave radiation of bare arable lands on a global scale incorporating their roughness
摘要： Smoothing soil surfaces, which had previously been deeply plowed, increases their albedo, which results in a lower amount of shortwave radiation being absorbed by their surface layer. Those surfaces emit less long-wave radiation too, leading to a reduction in their surface temperature, which can affect the climate. This paper quantitatively estimates the highest possible amount of shortwave radiation that could be reflected throughout the year from bare soils on arable land in the most extensive agricultural regions, where major crops are cultivated, on six of the Earth’s continents. The estimation refers to the highest levels of soil radiation occurring during clear-sky conditions without any clouds when the surfaces that had been conventionally tilled were bare for several days or more after the day of planting and were air-dried in two extreme roughness states: those formed by a plow and a smoothing harrow. The annual dynamics of reflective shortwave radiation of the bare soils were obtained using vectorized and rasterized geostatistical data sets about the areas of the soils and periods when they were bare, as well the spectra of the soil units that occupied the majority of these areas. Adding together all of the diurnal amounts of shortwave radiation reflected from the bare soils for each of the regions in the world, it was found that their radiation peak, appearing on the 140th days of the year, can reach about 22 EJ/day for soils treated by a plow, and a further 3 EJ/day when they are smoothed by a smoothing harrow.
关键词： Shortwave radiation,Soil roughness,Bare soil albedo,Annual variations
更新于2025-09-04 15:30:14
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[IEEE 2018 IEEE International Conference on Semiconductor Electronics (ICSE) - Kuala Lumpur (2018.8.15-2018.8.17)] 2018 IEEE International Conference on Semiconductor Electronics (ICSE) - A Study on the Atomic Topography of Nanostructured TiO<inf>2</inf>Thin Films: Effect of Annealing
摘要： Titanium dioxide (TiO2) is one of the most investigated metal oxides due to the wide range of applications such as photocatalysts. Photocatalytic activity will increased when the surface area is higher. Hence, this research focus on the surface topography and roughness of nanostructured TiO2 films characterized by atomic force microscopy (AFM) in order to obtain thin films with the optimum roughness for photocatalytic activity. TiO2 thin films were prepared by spin coating method at room temperature. The TiO2 solutions of 0.1 - 0.2 M were synthesized from titanium butoxide in ethanol. TiO2 films were deposited on the silicon substrates and annealed at 450°C. The results shown when the film was annealed, the grain were clearly observed. The grain size and the roughness increased when the film were annealed at high temperature. 0.2 M of TiO2 thin film exhibit the higher roughness with Ra and RMS values were 51.29 and 78.90 nm, respectively.
关键词： Molarity,Roughness,TiO2,Topography,AFM
更新于2025-09-04 15:30:14
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Perception of light source distance from shading patterns
摘要： Varying the distance of a light source from an object alters both the intensity and spatial distribution of surface shading patterns. We tested whether observers can use such cues to infer light source distance. Participants viewed stereoscopic renderings of rough objects with diffuse and glossy surfaces, which were illuminated by a point source at a range of distances. In one task, they adjusted the position of a small probe dot in three dimensions to report the apparent location of the light in the scene. In a second task, they adjusted the shading on one object (by moving an invisible light source) until it appeared to be illuminated from the same distance as another object. Participants’ responses increased linearly with the true light source distance, suggesting that they have clear intuitions about how light source distance affects shading patterns for a variety of different surfaces. However, there were also systematic errors: Subjects overestimated light source distance in the probe adjustment task, and in both experiments, roughness and glossiness affected responses. We find the pattern of results is predicted surprisingly well by a simplistic model based only on the area of the image that exceeds a certain intensity threshold. Thus, although subjects can report light source distance, they may rely on simple—sometimes erroneous—heuristics to do so.
关键词： lighting,reflectance,gloss,roughness,light source,illumination,material perception
更新于2025-09-04 15:30:14
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Designing an anisotropic noise filter for measuring critical dimension and line edge roughness from scanning electron microscope images
摘要： The scanning electron microscope (SEM) is often employed in inspecting patterns transferred through a lithographic process. A typical inspection is to measure the critical dimension (CD) and line edge roughness (LER) of each feature in a transferred pattern. Such inspection may be done by utilizing image processing techniques to detect the boundaries of a feature. Since SEM images tend to include a substantial level of noise, a proper reduction of noise is essential before the subsequent process of edge detection. In a previous study, a method of designing an isotropic Gaussian filter adaptive to the noise level was developed. However, its performance for relatively small features was not so good as for large features, especially in the case of LER. The main objective of this study is to improve the design method such that the accuracy of the measured CD and LER is not deteriorated substantially as the feature size decreases. The new design method allows a Gaussian filter to be anisotropic for the better adaptability to the signal and noise, both of which show a substantial level of directional correlation. The cutoff frequency for the direction normal to features is determined to include most of the signal components, and the cutoff frequency in the other direction is set to balance the signal and noise components to be included. This procedure enables a systematic and easy design of the filter. Also, the method of estimating the noise has been modified for higher accuracy. The performance of the new design method has been thoroughly analyzed using the reference images for which feature boundaries are known. It has been shown that the anisotropic filter designed by the proposed method performs better than the isotropic filter from the viewpoint of CD, LER, and power spectral density accuracy.
关键词： critical dimension,image processing,anisotropic noise filter,scanning electron microscope,line edge roughness
更新于2025-09-04 15:30:14
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Graphene-Oxide and Hydrogel Coated FBG-Based pH Sensor for Biomedical Applications
摘要： A hydrogel coated fibre grating-based pH sensor for biomedical applications has been realised, where Graphene Oxide (GO) had been used to enhance the bonding between the coating and the fibre. Two methods of deposition of GO were analysed i.e., evaporation and co-electroplating. The paper concludes that the system of GO evaporated on the fibre + the hydrogel has a sensitivity much higher, (6.1 ± 0.5) pm/pH, than the system of Cu and GO co-electroplated + the hydrogel, (1.9 ± 0.1) pm/pH, for a pH range between 2 to 10. The other conclusion is that the first system has a less coating bonding energy with the optical fibre whereas the second system has a stronger bonding energy, with better durability.
关键词： FBG,surface functionalisation,pH,sensing,fibre optic,biomedical application,roughness,graphene oxide,wettability,GO
更新于2025-09-04 15:30:14
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Fabrication of high fill-factor aspheric microlens array by dose-modulated lithography and low temperature thermal reflow
摘要： A cost-effective fabrication method for high quality and high fill-factor aspheric microlens arrays (MLAs) is developed. In this method, the complex shape of aspheric microlens is pre-modeled via dose modulation in a digital micromirror device (DMD) based maskless projection lithography system. Digital masks for several bottom layers are replaced from circle to hexagon for the purpose of enhancing the fill-factor of MLAs, then a low temperature thermal reflow process is conducted, after which the average surface roughness of microlens is improved to * 0.427 nm while the pre-modeled profile keeps unchanged. Experimental results show that the fabricated aspheric MLAs have almost 100% fill-factor, high shape accuracy and high surface quality. The presented method may provide a promising approach for rapidly fabricating high quality and high fill-factor aspheric microlens in a simple and low-cost way.
关键词： high fill-factor,dose-modulated lithography,aspheric microlens arrays,surface roughness,low temperature thermal reflow
更新于2025-09-04 15:30:14