scholarly journals Two-fluid computations of plasma block dynamics for numerical analyze of rippling effect

2005 ◽  
Vol 23 (4) ◽  
pp. 433-440 ◽  
Author(s):  
S. JABŁONSKI ◽  
H. HORA ◽  
S. GŁOWACZ ◽  
J. BADZIAK ◽  
YU CANG ◽  
...  
Keyword(s):  
Laser Irradiation ◽  
Laser Intensity ◽  
Short Pulse ◽  
Broad Band ◽  
Numerical Computations ◽  
Intensity Range ◽  
Two Fluid

In this paper the results of numerical computations of rippling smoothing basing on the broad-band laser irradiation method for the laser intensity range 1016−1017 W/cm2 and short-pulse (<10 ps) interaction with plasma are described.

Chronic Laser Exposure Effects on Rabbit Retina

1972 ◽  
Vol 30 ◽  
pp. 54-55
Author(s):  
Burton B. Silver ◽  
Theodore Lawwill
Keyword(s):  
Laser Irradiation ◽  
Laser Light ◽  
Broad Band ◽  
Argon Laser ◽  
Atropine Sulfate ◽  
Ultrastructural Changes ◽  
Laser Exposure ◽  
Rabbit Retina ◽  
Histological Changes ◽  
Threshold Doses

Dutch-belted 1 to 2.5 kg anesthetized rabbits were exposed to either xenon or argon laser light administered in a broad band, designed to cover large areas of the retina. For laser exposure, the pupil was dilated with atropine sulfate 1% and pheny lephrine 10%. All of the laser generated power was within a band centered at 5145.0 Anstroms. Established threshold for 4 hour exposures to laser irradiation are in the order of 25-35 microwatts/cm2. Animals examined for ultrastructural changes received 4 hour threshold doses. These animals exhibited ERG, opthalmascopic, and histological changes consistent with threshold damage.One month following exposure the rabbits were killed with pentobarbitol. The eyes were immediately enucleated and dissected while bathed in 3% phosphate buffered gluteraldehyde.

scholarly journals Beam-smoothing effect in broad-band random-phase irradiation

1993 ◽  
Vol 11 (2) ◽  
pp. 385-390 ◽  
Author(s):  
I. Matsushima ◽  
Y. Owadano ◽  
Y. Matsumoto ◽  
I. Okuda ◽  
T. Tomie ◽  
...  
Keyword(s):  
Laser Irradiation ◽  
Optical System ◽  
Random Phase ◽  
Broad Band ◽  
Laser Fusion ◽  
Phase Plate ◽  
Smoothing Effect ◽  
Broad Bandwidth ◽  
A New Technique ◽  
Focusing Lens

A new technique to achieve smooth laser irradiation profiles on laser fusion targets is evaluated numerically and experimentally. In this technique, smoothing is obtained by using a spectral dispersing optic and a random-phase plate placed in front of a focusing lens employing the broad-bandwidth of KrF lasers. Experimental results and numerical calculations agree well, verifying that this simple optical system is effective for smooth irradiation on targets.

Short-pulse neodymium:yttrium–aluminium garnet (Nd:YAG 1064 nm) laser irradiation photobiomodulates mitochondria activity and cellular multiplication of Paramecium primaurelia (Protozoa)

2017 ◽  
Vol 61 ◽  
pp. 294-304 ◽  
Author(s):  
Andrea Amaroli ◽  
Alberico Benedicenti ◽  
Silvia Ravera ◽  
Steven Parker ◽  
Wayne Selting ◽  
...  
Keyword(s):  
Laser Irradiation ◽  
Short Pulse

Fabrication of High Density Silicon Nano-Dots by Excimer Laser Irradiation on Block Copolymer Masks

2007 ◽  
Author(s):  
Dae Up Ahn ◽  
Erol Sancaktar
Keyword(s):  
Laser Ablation ◽  
Block Copolymer ◽  
Laser Irradiation ◽  
Excimer Laser ◽  
Ablation Threshold ◽  
Laser Intensity ◽  
Selective Etching ◽  
Time Duration ◽  
Excimer Laser Ablation ◽  
Excimer Laser Irradiation

We report easy and fast fabrication methods to prepare densely packed polystyrene (PS) and silicon nano-dots using one-step excimer laser irradiation on cylindrically nanopatterned block copolymer materials, without any additional selective etching steps before a non-selective etching. Preferential etching in more ultraviolet (UV)-sensitive block component, and non-selective removal of all block components allowed transferring nanopatterns in block copolymer masks to inorganic silicon substrates, when an appropriate laser intensity was used. Surface melt flows of block components, which severely undermine the initial orders of nanopatterns in a block copolymer mask, were observed at the laser intensity near the ablation threshold of the less UV-sensitive component. Thus, in order to obtain mask-image-like topographic nanopatterns on the target material surfaces, the intensity of excimer laser radiation should be sufficiently lower than the ablation threshold of the less UV-sensitive component as long as the intensity is higher than that of the more UV-sensitive component. Numerical analyses on the photothermal excimer laser ablation in binary mixture systems predicted the presence of a matrix-assisted excimer laser ablation in the less UV-sensitive component at the laser intensity lower than its ablation threshold, owing to the heat conduction from the more UV-sensitive component during the nanoscopic level of time duration.

Formation of Electro-Conductive Part on Polymeric Material Surface by CO2 Laser Irradiation

2011 ◽  
Author(s):  
Takushi Saito ◽  
Tatsuya Kawaguchi ◽  
Isao Satoh
Keyword(s):  
Electrical Conductivity ◽  
Laser Irradiation ◽  
Polymeric Material ◽  
Carbon Dioxide Laser ◽  
Laser Intensity ◽  
Material Surface ◽  
Small Disk ◽  
Electrically Conductive ◽  
Higher Temperature ◽  
Property Changes

In this study, a method to directly form an electrically conductive layer on the surface of polymeric material by using infrared laser irradiation was investigated. Polyacrylonitrile, which was shaped into a small disk 20 mm in diameter and 5 mm thick, was used as a test specimen. The conditions for pyrolysis were obtained by referencing the conditions for commercial carbon fiber. First, the specimen was processed in air at a relatively low temperature (around 250°C) for the stabilization treatment (i.e., fireproofing), then its surface was heated at a higher temperature (above 1000°C) for the carbonization treatment (i.e., graphitizing). Both an infrared furnace and a carbon dioxide laser were used as heating devices to find optimal conditions. Property changes in the material due to the thermal treatment were measured using Fourier transform infrared spectroscopy, and the electrical conductivity of the carbonized surface was measured using a four-probe method. The results showed that an electrical conductivity of 11.4 S/cm (siemens per centimeter) was achieved with a laser intensity of 8.6 W/cm2 for 5 min for the stabilization, and a laser intensity of 34 W/cm2 for 10 s for the carbonization.

Structural and optical transformations by laser irradiation of InSb-based thin films

1990 ◽  
Vol 5 (1) ◽  
pp. 190-201 ◽  
Author(s):  
J. Solis ◽  
K. A. Rubin ◽  
C. Ortiz
Keyword(s):  
Thin Films ◽  
Stress Relaxation ◽  
Laser Irradiation ◽  
Laser Annealing ◽  
Short Pulse ◽  
Amorphous State ◽  
Minimum Time ◽  
Optical Microstructure ◽  
Order Of Magnitude ◽  
Ion Laser

The effect of 647 nm Kr-ion laser irradiation on small, 1 μm diameter regions of (In0.43Sb0.57)0.87Ge0.13 and In0.43Sb0.57 amorphous as-deposited thin alloy films was determined. Laser irradiation times of 50 ns-20 μs produced three distinct reflectivity states which differed from the original as-deposited values for both alloys. Both alloys exhibited an amorphous state of increased reflectivity after short pulse (∼100 ns to ∼500 ns) laser irradiation which has not been previously observed. Slightly longer pulses caused surface corrugations to form in these high reflectivity regions. The formation of corrugations was consistent with stress relaxation. Further laser annealing caused crystallization and decreased reflectivity. The addition of Ge increased the minimum time to crystallize by one order of magnitude, inhibited the precipitation of pure Sb crystals, and caused crystallites to nucleate at the spot edge rather than from the center of the spot. Optical, microstructure, and electrical changes were correlated. SEM and TEM showed that regions of similar reflectivity could result from significantly different microstructures.

Laser-Induced Deformation Patterns in Thin Films and Surfaces

1999 ◽  
Vol 121 (2) ◽  
pp. 182-188 ◽  
Author(s):  
Daniel Walgraef
Keyword(s):  
Thin Films ◽  
Laser Irradiation ◽  
Surface Deformation ◽  
Laser Intensity ◽  
Laser Beams ◽  
Experimental Investigations ◽  
Relative Importance ◽  
Periodic Patterns ◽  
One Dimensional ◽  
Deformation Patterns

The coupling between surface deformation and defect motion may be at the origin of deformation patterns in thin films under laser irradiation. We analyze the dynamics of laser-induced vacancy densities and deformation fields and show how it triggers deformational instabilities, in the case of uniform and focused laser irradiation. Pattern selection analysis is performed, through linear, nonlinear, and numerical methods. In irradiation with extended beams, we show that, according to the relative importance of nonlinearities arising from the defect or from the bending dynamics, square, hexagonal or even quasi-periodic patterns are selected. It appears, furthermore, that one-dimensional gratings are always unstable in isotropic systems. In irradiation with focused laser beams, rose deformation patterns, with petal number increasing with laser intensity, naturally arise in this model, in qualitative agreement with experimental observations. These results claim for more systematic and quantitative experimental investigations of deformational pattern formation under laser irradiation.

Recurring Molecular Alignment Induced by Pulsed Nonresonant Laser Fields

2001 ◽  
Vol 66 (7) ◽  
pp. 991-1004 ◽  
Author(s):  
Long Cai ◽  
Břetislav Friedrich
Keyword(s):  
Laser Pulse ◽  
Laser Field ◽  
Analytic Solution ◽  
Short Pulse ◽  
Molecular Alignment ◽  
Time Dependent ◽  
Molecular Axis ◽  
Linear Molecule ◽  
Numerical Computations ◽  
Laser Fields

We examine the rotational wavepackets created by the nonadiabatic interaction of a linear molecule with a pulsed nonresonant laser field. We map out the recurrences of the wavepackets and of the concomitant alignment as a function of the duration and intensity of the laser pulse. We derive an analytic solution to the time-dependent Schrödinger equation in the short-pulse limit and find it to agree quantitatively with our numerical computations. This indicates that the recurrences are favored under an impulsive transfer of action from the radiative field to the molecule. The recurring wavepackets afford field-free alignment of the molecular axis.

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