Rough Surface Materials Research Articles

Computational Performance of GTD-RT Applied for Evaluation of Electromagnetic Scattering on Rough Surfaces

In this paper, a new robust computational method that applies the geometrical theory of diffraction (GTD) in conjunction with the ray tracing (RT) technique is developed to evaluate the electromagnetic scattering pattern due to a plane wave represented as beam of parallel rays incident on a rough surface of quite arbitrary statistical parameters. The development of the proposed technique is explained in detail taking into consideration the generation of the geometrical model of the rough surface. The Fresnel reflection model is applied under the assumption of arbitrary electrical and optical properties of the rough surface material. Also the polarization of the plane wave primarily incident on the rough surface is taken into consideration. The algorithm developed in the present work accounts for multiple bounces of an incident ray and, hence, it can be considered arbitrary higher-order GTD-RT technique. The accuracy of the obtained results is verified through the comparison with the experimental measurements of the scattering pattern of a light beam incident on rough sheets with specific statistical properties. The numerical results of the present work are concerned with investigating the dependence of the scattering pattern on the surface roughness, refractive index, angle of incidence, and the resolution of the geometric model of the rough surface. Also, it is shown that, for limited resolution of the rough surface model, the accuracy of the calculated scattered field depends on the angle of incidence of the primary beam and the surface roughness.

Dielectric surface roughness scattering induced crosstalk performance of coupled MCB interconnects

A CMOS inverter driven equivalent single conductor model of capacitively coupled mixed CNT bundle (MCB) interconnects are taken to analyze the crosstalk induced time domain and frequency domain behaviors at 14 nm technology node for a temperature range (300–500 K). Four possible structures of MCB (e.g.S1, S2, S3 & S4) are analyzed by considering the dielectric substrate materials induced scattering. The most typical and consistent dielectric materials like silicon dioxide (SiO2), boron nitride (BN) and silicon carbide (SiC) are taken into account for studying the behavior of MCB depending upon dielectric surface roughness (DSR) scattering. A complete crosstalk (dynamic & functional) effect in terms of positive peaks, time duration and area of rise glitch is studied. The results revealed that MCB structure ‘S4’ is having less delay and more 3-dB frequency bandwidth in comparison to other structures of MCB. Moreover, S4 placed on SiC substrate material is depicting best results among other substrate materials. The bode stability of ‘S4’ on smooth surface and rough surface material is analyzed to validate the performance of ‘S4SiC’ in terms of phase and gain margin. It is also observed that the 3-dB frequency bandwidth of ‘S4SiC'reduces with increase in temperature. Consequently, the amplitude of surface roughness parameter (δsr) plays an important role to analyze the performance of coupled interconnects of MCB in deep sub-micron (DSM) regime.

Multimaterial Capability of Laser Induced Plasma Micromachining

Presently surface microtexturing has found many promising applications in the fields of tribology, biomedical engineering, metal cutting, and other functional or topographical surfaces. Most of these applications are material-specific, which necessitates the need for a texturing and machining process that surpasses the limitations posed by a certain class of materials that are difficult to process by laser ablation, owing to their optical or other surface or bulk characteristics. Laser induced plasma micromachining (LIPMM) has emerged as a promising alternative to direct laser ablation for micromachining and microtexturing, which offers superior machining characteristics while preserving the resolution, accuracy and tool-less nature of laser ablation. This study is aimed at understanding the capability of LIPMM process to address some of the issues faced by pulsed laser ablation in material processing. This paper experimentally demonstrates machining of optically transmissive, reflective, and rough surface materials using LIPMM. Apart from this, the study includes machining of conventional metals (nickel and titanium) and polymer (polyimide), to demonstrate higher obtainable depth and reduced heat-affected distortion around microfeatures machined by LIPMM, as compared to laser ablation.

Vapor‐phase Staining of Cyanoacrylate‐Fumed Latent Fingerprints Using p‐Dimethylaminobenzaldehyde

Contrasting or enhancing of cyanoacrylate ester-fumed latent fingerprints deposited on solvent-sensitive materials such as oil marker writings and rough surface materials such as unglazed earthenware is not easy by conventional dye solutions dipping or dye powder dusting. In this study, a new vapor-phase staining method using p-dimethylaminobenzaldehyde (DMAB) is proposed for staining such materials. DMAB has high volatility and selective absorbability to cyanoacrylate-fumed fingerprints, so that cyanoacrylate-treated samples can be easily stained by leaving them simply in a closed container along with DMAB crystals for 48-96 h at room temperature or in conjunction with the use of mild heating. The stained fingerprint could be excited by UV irradiation (365 nm), and the fluorescent fingerprint was photographed through a UV cut-off filter (420 nm). The new method achieved minimally destructive fluorescent staining for the solvent-sensitive samples and the rough surfaced samples.

Analysis of plume deflection in the silicon laser ablation process

Changes in target surface morphology and ablation plume direction have been experimentally observed during the initial stages of the silicon laser ablation process. A relationship between both phenomena can be observed upon analysing the temperature field induced by the laser beam in a rough surface material. Theoretical studies on the deflection of the ablation plume are presented. These analyses are based on the hypothesis that particles that reach evaporation temperature will exit normally to the target surface with a velocity that is proportional to the surface temperature and the amount of the ablated material. Numerical solutions and experimental results of laser ablation process of silicon targets are found to agree with theoretical studies.

イメージングプレートによる粗表面汚染密度測定

Floating radioluminography using an imaging plate can be sufficiently applied to the monitoring of the surface contamination on rough surface materials at a radioisotope facility. This technique is superior to the smear method which has been used to estimate the contamination of low energy β-ray emitters, because the fixed contamination and the contamination on the coarse surface materials have been difficult to be wiped out on a smear paper. The radiation detection efficiency of the imaging plate is as high as the liquid scintillation technique, when the plate is exposed with the sample in a vacuum chamber. In this study, the technique has been tested to the surface monitoring of a liquid-waste concrete cistern, and the sort of contaminant radioisotope was estimated by inserting a plastic film or an aluminum plate between the imaging plate and the sample.

Analysis and prediction of laser scattering from rough-surface materials

Previous analytical efforts are extended and combined to describe the intensity of laser radiation scattered bidirectionally from rough-surface materials. Two scales of roughness are employed to effectively model rough-surface scattering phenomena. Laser scattering distributions are computed and compared with experimental data. The internal consistency and frequency dependence of model parameters, derived from data comparisons, are examined. Model parameter analyses and data comparisons support the validity of the scattering model.