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An analytical solution is developed for thermal stress in exponentially time decaying laser short-pulse heating of a metallic surface. Because the heating duration is short, a nonequilibrium heating model incorporating the electron kinetic theory approach is used to formulate the temperature distribution during the laser heating pulse. Thermomechanical coupling is introduced in the analysis to formulate the thermal stress field. Thermodynamic irreversibility is considered and the entropy generation rate due to heat transfer and thermal stress field is formulated during the heating process. It is found that temperature decays gradually in the surface region and becomes sharp as the distance increases towards the solid bulk. Thermal stress is compressive in the irradiated region. Thermodynamic irreversibility due to heat transfer dominates thermodynamic irreversibility because of the thermal stress field. PACS No.: 44.10.+i. Nous presentons une solution analytique pour la contrainte thermique due a une impulsion laser a decroissance exponentielle sur une surface metallique. Parce que le chauffage est de courte duree, nous utilisons un modele de chauffage hors d'equilibre incorporant la theorie cinetique des electrons afin de formuler la distribution de temperature pendant l'impulsion laser. L'introduction d'un couplage thermomecanique permet de decrire le champ de contrainte thermique. Nous tenons compte de l'irreversibilite thermodynamique et nous formulons le taux de generation d'entropie du au transfert de chaleur et au champ de contrainte thermique pendant le processus, pour trouver que la diminution de temperature qui est graduelle dans la region du chauffage devient rapide a distance. La contrainte thermique est compressive dans la region du chauffage. L'irreversibilite thermodynamique due au transfert de chaleur est plus importante que celle due a la contrainte thermique. [Traduit par la Redaction], Introduction Laser short pulse heating of metallic surfaces involves nonequilibrium energy transport in the irradiated region. Electron and lattice subsystems separate thermally because of electron temperature increases through energy absorption [...]

We analyze the focusing properties of Fresnel zone plates fabricated over steel tapes using laser ablation. Our intention is to implement the use of micro-optical elements when the use of conventional chrome-glass elements is not indicated. Because of the manufacture process, the surface presents a certain anisotropic roughness, which reduces the focusing properties. First, we develop numerical simulations by means of the Rayleigh--Sommerfeld approach, showing how roughness in both levels of the Fresnel zone plate affects the focalization of the lens. We also manufacture Fresnel zone plates over steel tape, and perform experimental verification that corroborates the numerical results. [c] 2010 Optical Society of America OCIS codes: 050.1965, 240.3990, 240.5770.

The robustness of the hole target against laser parameter changes in a laser spot size and in a laser pulse length against a contaminated proton source layer and against a laser alignment error are described. The multiple-hole target is robust against a laser alignment error and a target positioning error and it has served as a robust target for practical uses to produce a collimated proton beam.

In the field of industrial vision, the three-dimensional inspection of highly reflective metallic objects is still a delicate task. We deal with a new automated three-dimensional inspection system based on polarization analysis. We first present an extension of the shape-from-polarization method for dielectric surfaces to metallic surfaces. Then, we describe what we believe to be a new way of solving the ambiguity concerning the normal orientation with an active lighting system. Finally, applications to shape-defect detection are discussed, and the efficiency of the system to discriminate defects on specular metallic objects made by stamping and polishing is presented. OCIS code: 110.6880

We use the finite-difference time-domain (FDTD) method to model the spectral properties of frequency-selective surfaces (FSSs) at normal incidence in the 1-10 [micro]m wavelength. At these wavelengths the usual assumption that the metallic portions of a FSS are infinitesimally thin perfect conductors are no longer valid. We include the effects of dispersive complex conductivity for real metals and dispersive permittivity for dielectric materials by developing a unified approach that is especially suited for use in FDTD simulations. We concentrate on the finite nature of the metallic conductivity and its variation with wavelength in FSS structures. Our simulation results indicate that the resonant spectrum of a FSS in this wavelength range depends not only on the geometry of the structure and the dielectric substrate present, but also critically on the dispersive properties of the metal species used for the conductors. OCIS codes: 000.4430, 160.3900, 160.4760, 260.2030, 260.3910.

We present a procedure that compensates for phase aberrations in digital holographic microscopy by computing a polynomial phase mask directly from the hologram. The phase-mask parameters are computed automatically without knowledge of physical values such as wave vectors, focal lengths, or distances. This method enables one to reconstruct correct and accurate phase distributions, even in the presence of strong and high-order aberrations. Examples of applications are shown for microlens imaging and for compensating for the deformations associated with a tilted thick plate. Finally we show that this method allows compensation for the curvature of the specimen, revealing its surface defects and roughness. Examples of applications are shown for microlenses and metallic sphere imaging. OCIS codes: 090.1760, 090.1000, 180.0180, 120.5050, 120.3620.

Anomalous field enhancement occurs between two-plasmon-resonant surfaces. This model is expected to be useful for metal surfaces having roughness.

Research into void dynamics in relation to the critical morphological evolution is presented. This work was designed to identify the circumstances under which premature failure of metallic thin interconnects arises. The significance of the surface diffusion anisotropy for the premature creation of a fatal open circuit configuration is highlighted.

The changes in the microtopography of a metal surface during a corrosion process are measured by decorrelation of the scattered speckle fields under coherent illumination. For that purpose a quantitative relation between the decorrelation of the scattered light fields and the rate of corrosion is established in a theoretical model, based on the statistics of phase and reflectivity changes of point scatterers at the surface. The speckle fields are recorded by a CCD camera and processed numerically in a computer, yielding the standard deviation of the topography changes with nanometer sensitivity. From the analysis of a series of images taken at equal time intervals during the corrosion process, the degree of interrelation among subsequent topography changes is calculated.

A study was conducted to analyze electron transport in an atom-sized bridge between a metal surface and a tip of a scanning tunneling microscope. The perturbation technique was utilized to determine the self-energy against the Coulomb interaction within a single-site approximation. The electric current was then obtained by solving the Lippmann-Schwinger equation. Experimental results indicated that increases in temperature dependence correlated with the strength of the Coulomb interaction.

Excimer-laser-induced ablation has been used to produce surface structuring of various metals. Such structuring contributed to a 5-15% enhancement of the bonding strength of these metals when a commercial adhesive was used.

In this study the effects of intense excimer laser irradiation (10 to the eighth power-10 to the ninth power W cm to the -2) on some radiative properties of copper, aluminum, magnesium, tantalum, and molybdenum are investigated. The short pulse duration of the excimer laser (30 ns FWHM) and the wavelength of the radiation initiate a processing regime that is dominated by the effects of a laser-supported plasma above the workpiece surface. A laser- supported detonation wave is observed that acts on a thin molten surface layer. The resultant structure that is frozen on the surface is dependent on the thermophysical properties of the metal and the number and manner in which multiple pulses are applied to the surface. This surface roughness has features on both the macro- and microscopic scale that affect the radiative properties of the surface. The surface plasma also initiates very fast reaction rates that can create a thick oxidized layer on the metal surface. The surface oxide layer may either be lightly (CuO particles on a copper substrate) or tightly adhered (Al2O3 on aluminum) to the surface. The effect of excimer laser irradiation is characterized with scanning electron microscopy and Fourier transform infrared spectroscopy. Data on solar absorptivity Alpha(sub s), spectral reflectivity Rho prime(Lambda), bidirectional reflectivity Rho double prime(Lambda), and total near-normal total emissivity Epsilon prime(Tau) are also presented that show that in some cases heavily irradiated samples simulate the radiative behavior of a flat absorber.

Conductivity and permeability vary as a function of depth in the near-surface region in the frequency-dependent impedance of right-cylindrical air-core eddy-current probes over thick metal plates. An impedance analyzer was used to measure the probe impedance from 1kHz to 1MHz. The theory was tested by using precision-wound air-core coils, and industrial practice was connected to commercial eddy-current probes. Uniform plates of metals, covered with many thin, discrete layers of other metals and core-hardened titanium plates with smoothly and continuously varying near-surface conductivity as a function of depth, were used to model a continuous profile. Stacking many thin layers with differing conductivities can simulate continuous profiles, and the conductivity change affects the probe in impedance change.

The permeation processes in the bulk, the surface/bulk and gas/surface interfaces which affect hydrogen transport in metals were investigated using models. The results showed that the permeation process was characterized by three distinct mechanisms: rate limiting absorption upstream, rate limiting desorption downstream and bulk saturation. Permeating flux saturation brought about by rate limiting absorption upstream occurred at pressures greater than that required in saturation of upstream surface coverage.

The effects of low energy bombardment of a Cu surface by Cu atoms were investigated using molecular-dynamics simulations. The results showed that vacancies were formed only near the surface while interstitials were produced further inside. The bombarding energy greatly detrmined the degree of defect production. The amount of interstitials was significantly decreased by changing the perpendicular incidence.

Ascanning tunneling microscopewas used to assist the growth of nanometer-scale uniform gold stripes on reconstructed Au(111) surfaces. The microscope tip was used to produce stripes several 100 nm in length and separated by spaces ranging from two to four nm. Stripes were formed only when the scan direction was towards the direction of reconstruction. The growth was observed to be faster than that seen in diffusion alone.

A study was conducted on the use of the relaxation method in determining surface crack size and shape in metallic structures. The approach is entirely numerical in nature and uses measurements taken from the crack vicinity itself. Synthetic input and noisy data were used in the study. The alternate current potential difference technique was used as a basis for the new approach.

Functionally graded multiferroic composites are examined in order to design the electromagnetic properties of synthetic surface and material surfaces. The results have shown that the amplitudes of the field response along the direction of the compositional gradient can be either matched to a uniform material or systematically reduced and Green's functions are used for studying the electric dipole-induced electric and magnetic potentials in the graded multiferroics.

Several studies are conducted to explain the surface charge induced variations observed in the electrical conductivity of nanoporous gold during the charging and decharging of the metal surface. The effective thickness of the ligands is also shown to highly affect the conductivity of the metal.

The scheme of electron acceleration that has used resonant interaction of electrons with a surface plasma wave is used in accelerating electrons to higher energies with the control in their trajectories. The configuration of two parallel surfaces separated by a vacuum region has supported a surface plasma wave that has propagated parallel to the metal surfaces with amplitude maxima on the two surfaces and a minimum in the middle.

The article presents surface-enhanced Raman scattering process by a spectroscopic method to boost 14-order-of-magnitude that changes the weak inelastic-scattering effect into a single-molecule level.

Ray tracing using Nd:YAG laser is used to study the absorption of light by smooth and rough surfaces. The results show that in light incident at a tangent to the surface, the absorptance is found to rise, fall, and rise again with increase in surface roughness due to multiple scattering.

The scanning electron microscope analysis has shown that nanoholes of approximately 25-50 nm in diameter, arranged in one-dimensional (1D) and two-dimensional (2D) irregular and regular arrays, are formed. The results conclude that nanoporosity can be generated on metal surfaces by nanosecond laser-matter interactions in the semi-confined configuration.

The characteristics of luminescence that is induced by high-velocity impacts of metallic particles on metal surface are analyzed. The analysis has shown that the intensity of luminescence depends not only on the energy of the impinging particles and on the stresses produced on impact but also on the particular combination of materials and of the particles and the plate.

The basic characteristics of the near-field intensities of the proposed I -shaped aperture in the pyramidal structure is investigated which would provide high emission intensity and small spot size simultaneously. It was found that the I-shaped aperture in the pyramidal structure had a higher near field intensity and much smaller spot size than those of conventional simple square aperture.

The molecular dynamics simulations are used to investigate the ion beam induced smoothening of crystalline and amorphous substrates. Low energy recoil events in an amorphous substrate lead to the sinking of a nanoparticle indicating that thermal spikes are not required for radiation-induced viscous flow.

Investigation was carried out on the molecular orientation dependence of the o-p conversion of H(sub 2) interacting with a metal surface and the conversion yield for a perpendicular orientation is larger than that for a parallel orientation. The results not only show a strong dependence on the orientation of the H-H bond with respect to the surface, but also on the H(sub 2) c.m. distance from the surface.